The problems being seen there sound more like video drivers plus another gig of memory wouldn't hurt. If new supply happens to be a cheapo lacking good regulation or simply not seeing enough amps on the 12v rails that would cause other problems.
Lock ups when running a game are generally video or sound related problems. Out of memory errors are usually the result of a drive reaching capacity and ismply lacking space for the paging file Windows creates for virtual memory. What to do?
1)Spyware Terminator provides a registry shield while not being resource hungry.
2)If you are running the 7.1 or 7.5 build of the AVG free edition go for the latest 8.0 release since that no longer interferes with gaming as antivirus programs are known for.
3)If you are not using AIM that as well as the others can easily be disabled in the msconfig utility. If you still see problems you may have more then driver issues to solve. Not enough space on the hard drive, problems with system files, possible need for a clean install of Windows?!
Once a drive becomes too polluted with useless items like unused temp folders and a system registry is loaded with invalid entries Windows in general will start seeing a long list of problems appear. Or you may have simply seen a bad install with the video card's drivers if not the wrong version.