"If you can boot the system back, you could try a System File Check,
sfc /scannow
It will probably ask you for your installation disk to recover corrupted system files (if any).
If you cannot boot, you should try a system recovery with your install disk.
Update: If you doubt the hard-drive or would like to confirm any other hardware dependencies (though, from your description, i do not doubt the RAM), you could boot with a Ubuntu LiveCD and do some diagnostics.
memtestx86 will check your RAM (Ubuntu LiveCD boot option)
SMART tools can be used to analyze your hard-disk state You could also use HDTune from your Windows Vista (if it remains up for some time) On Ubuntu you will need the smartmontools (not sure if that comes with the LiveCD The command will be: sudo smartctl -a /dev/hda (replace hda with your Vista disk)
Notes to setup a LiveCD and get SMARTMonTools.
Update2:
good to hear that it was just your memory and not the disk that was failing
I erred in thinking the memory did not sound bad (its always good to check the memory)
avelldiroll makes a good point about getting SMART tools with, sudo apt-get install smartmontools also, as pointed out, it would not remain with a LiveCD (need to get for each boot). I keep a USB installed Ubuntu handy for such life."
BlueScreenView scans all your minidump files created during 'blue screen of death' crashes, and displays the information about all crashes in one table. For each crash, BlueScreenView displays the minidump filename, the date/time of the crash, the basic crash information displayed in the blue screen (Bug Check Code and 4 parameters), and the details of the driver or module that possibly caused the crash (filename, product name, file description, and file version). For each crash displayed in the upper pane, you can view the details of the device drivers loaded during the crash in the lower pane. BlueScreenView also mark the drivers that their addresses found in the crash stack, so you can easily locate the suspected drivers that possibly caused the crash."
