Is it worth upgrading RAM on a Vista/Windows 7 64bit system with 1GB of PC2-4300

"Yes. For $60, i just upgraded an Inspiron 9300 running Windows 7 from 1GB to 2GB (the max) and i would have done 4GB if the laptop would support it. It ran W7 fine before but with more than one app open there was pretty significant and fairly regular disk thrashing. With 2GB it's calmed down quite a bit.

Looks like your motherboard supports up to 8GB. So, if you're running Windows 7 64-bit, put at least 4GB in, and up to 8GB. If 32-bit, then just do 4GB. You should definitely be able to notice a difference.

This is unsolicited (sorry), but if you want to stick with your system (not terribly outdated), i'd also look at getting a better graphics card. I had the excellent 6600GT in my previous tower system, but the 8800GT in my latest is worlds better. Win 7 loves a fast video card."

Put as much RAM as you can afford or will fit in that system. That will probably be your biggest bang for the buck on that system. I would also kill any start-up programs or background processes that you don't need.