Crucial.com will get you the right ram but 1GB is enough to run Windows 7. I know I ran it on 512MB during BETA days.
Ok, about your machine. There are some drivers you'll have to find. Search for wifi, video and such from sony.
Can I CHANGE my RAM Memory from PC-2100DDR, expandable to 1GB , to 2GB (1 x 1GB) ,333MHz-200 Pin PC2700 SO-DIMM "Notebook" Memory OR Other to Handle Win7 Req'mts?
BIOS: Award ACPI Rev. 1001, 8/20/2002, SMBIOS 2.3.
PROCESSOR: AMD Athlon Processor 2400 at 2GHz