Please save me from buying yet another laptop!!!!!

I sure hope someone here is kind enough to help me! I own a Sony VGN-FS920, for those of you that don't know the weak ass stats, here they are:

• 512 MB DDR2
• 80 GB
• M Processor 740 (that burns a whole in my leg at night)

I was having issues with my laptop being incredible slow, from booting to running programs. I went to Best Buy and purchased (2) 1 GB memory (Corsair VS1GSD667D2). Since then I have had issues with booting (physical memory dumping), and a very unstable machine. I removed just one memory chip to see if maybe I had a bad one and once I did that, it appeared to be working ok, but very slugglish. My programs were taking 25 to 45 seconds to load.

This morning I turned on my computer and it started to act back up again with the "physical memory dump" and I immediately took out the last new memory that I had purchased and placed in machine and replace with old 512 MB card, no more booting issues, but all programs are running so slow that it isn't worth having a computer.

I would assume after hearing this, that it would in fact have to do with my memory, but I can't imagine that I bought 2 lemons from the same place, is it possible that they are not compatable with this machine. Any help I can find would be wonderful and greatly appreaciated over here.

Check the voltage of the RAM you bought as well as the BIOS settings for your RAM if memtest86+ shows everything is OK