What are causing these installation problems?

Previously I only had 1 Gb memory, so bought 2x2gb memory making it a total of 4gb. The RAM I bought was same manufacturer, type, rates, cas and latency as shown:

Old memory 1gb: http://www.patriotmemory.com/produ [...] 594&type=1
New memory 4gb: http://www.newegg.com/Product/Prod [...] 6820220335

Motherboard: http://www.foxconnchannel.com/prod [...] -us0000172


After I installed it i started having problems playing TF2 and some programs became corrupt when I tried installing them, files wouldn't copy over etc. Ive ran Memorytest 3.4 and everything seems fine. I reformatted and put on XP64, however im still having problems. Steam and World ofWarcraft are corrupt and other installations like spydoctor, acrobat reader, Microsoft security updates and Word 2007 becomes corrupt when I try install them. Its always the same problem, some file cant copy over so it chokes and reverts the installation.

What may be causing all of this? Is it my new memory?

Ive re-installed my OS, ran defrag, checkdisk, memory3.4-test, I have ran hardware diagnostics and nothing comes up as wrong. I also installed the programs on another hard drive to see if its my drive but i get the same corruption errors. Please help!


What makes me think its my memory is because i recently installed it, and if i choose to install the same files that give me problem to another hard drive i get same installation errors. (at least on world of warcraft)