"Improved Memory Management: RAM is cheap and plentiful - 7 will use your RAM to speed up program loading and executing, which has a huge effect on system performance.
Improved UI: The new taskbar is more application orientated, rather than document orientated - XP's UI made sense at the time, but the world has moved on, and being able to more easily switch between many programs is a huge advantage.
Improved Search: I almost didn't put Improved in there, because XP's search... didn't really work, and when it did, it wasn't fast. 7's search is accessible from either the start menu, or any explorer window, and searches files, folders, and subfolders almost instantly. Much better.
Improved Driver Structure: This is 90% of the reason Vista was received badly - the way drivers interact with the OS was completely overhauled. The effect a few years down the line, is that drivers have a much harder time crashing your PC, making:
Improved Stability: Bringing down a Windows 7 system isn't easy. XP is quite stable, but 7 is solid as a rock.
Improved Security: The dreaded UAC, is in fact not as bad as it's made out to be. In the *nix world, nothing runs as root unless it has to - with UAC, neither do applications on windows. It's not perfect (far from it, Vista's was much better), but every little helps.
Improved Desktop Drawing: The Desktop Window Manager, responsible for all of the fancy glass effects, is a much faster way of drawing windows - meaning you spend less of those annoying moments where it takes half a second for the window below another to redraw - with 7, it's already there, instantly. It's also responsible for powering Aero Peek, the window previews you get when you hover over a taskbar preview.
All in all, 7 (and indeed, Vista) is a huge improvement over XP (because really, it's what? 8 years old now? It can't be expected to keep up with the times - it's is over), and is a hugely recommended upgrade for just about anybody - including netbook users."
The killer feature for me on my laptop is crazy fast hibernations. Yeah, it has a lot of other cool stuff, but nothing that I couldn't live without on XP or Vista. But hibernation on XP was basically broken and on Vista it took forever and a day. In Windows 7 I can hibernate and wake up in < 10 seconds which all of the sudden makes my laptop much more useful in a whole bunch of new ways. I can take notes and quickly run out to do something else, or use it to quickly look something up as needed. This is my favorite feature of Windows 7.
"the Windows 7 taskbar is quite impressive and offers some useful features indeed but i like to keep things simple and i'm more of a keyboard jockey anyway, so a flashy UI doesn't really do anything for me, besides most of these so called innovative improvements have been made available by 3rd party developers for XP, using far less resources than their Microsoft counterparts (e.g. AeroSnap, WinFlip and especially ViStart which is running circles around Windows Desktop Search).
on machines with more than 4 GB RAM i opt for Windows 7 x64 because it certainly is a major improvement over older 64-bit Windows operating systems, on other machines i'm perfectly happy with 32-bit Windows XP or Windows 2003 Server (still my favorite!) and i have yet to see programs XP can't run as good as Windows 7 (since i'm not much of a gamer i couldn't be bothered with DirectX 10 or 11)."
"I migrated from Vista to Win7 for one reason - improved taskbar. I often have around 20 windows open and I use ""Switcher"" which acts as ""Expose"" on Mac but it becomes more difficult to look for window with several windows... the Win7 taskbar tidies up nicely and lets me view all windows of each application rather than all windows of all applications. Desktop Window Manager is also much more robust.
Unexpected benefit is the search - it finally works! It looks what you're expecting for it to look for and that's significant if you have several thousand of files to deal with.
As for stability, since installing Windows 7, I don't recall a crash but I would never say it never crashes - all operating systems crash because they're written by humans making mistakes or that there's a defect in hardware but I can say that I don't have crashes as far as I remember.
Speed is slower although it may seem ""faster"" but that's the graphics doing the work. I suspect if I upgrade graphics card, it'd even be ""faster"" yet the overall CPU performance may be slower since Win7 has a lot more code to execute."
"Most of the answers here have focused on UI improvements, which I would agree are awesome additions. I think there are quite a few changes other than the UI which are noteworthy, too:
Networking: gone is the confusing ""simple file sharing"" from Windows XP. You can adjust custom options on network shares, or use a simple sharing wizard. You also tell Windows what type of network you're on when you connect to a new network, and it configures settings accordingly, so that your shared folders are available on your home network, but not on the network at the coffee shop's wifi. Troubleshooting: a lot of things can basically ""fix themselves"" now. The built-in troubleshooter seems to work pretty well for some hardware problems and such. Installation: You won't be installing windows all the time, but the process is much more user-friendly. Also, windows updates can be applied during the installation process if the computer's connected to the internet, making things easier. More devices get their drivers installed automatically now, too... rarely do you have to hunt on the OEM's website. Stability: Windows XP was pretty stable, but Windows 7 is even more so, from my experience, and this is on the exact same hardware I used to have XP on."
