Sony VAIO PCV-RS320 2GB RAM problem?

I have been trying to upgrade my RAM from 1GB to 2GB (which is the maximum allowed for my PC). The recommended specs are no greater than four 512MB cards of PC2700. I tried PC3200, and it didn't work (though two of the PC3200 would work - 1GB). I finally bought PC2700 (had to order it - couldn't find it in a store anywhere). 2GB of it doesn't work either. 1GB in any config (including a 1GB card - I've tried that, too) works, but no config of any RAM from 1.5GB to 2GB works. I've tried updating the BIOS. Didn't work. It was saved, but it still wouldn't boot up with 2GB. Sony support gave me a link to a BIOS update, but when I tried to install it it said it couldn't read my system info. Does anyone have an answer that will help me?!?!? Thanks!