There is one 512mb dimm chip and the spec. are DDR1 synchronous DRAM (SDRAM) at 333 MHz, expandable to 2.0 GB , PC2700 333MHz 200-pin Non-ECC Unbuffered DDR SDRAM SODIMM.
This is the memory I used at $52.99 and $5.00 shipping
"newegg.com/Product/Product.asp?Item=N82E16820141207"
pqi POWER Series 512MB 200-Pin DDR SO-DIMM DDR 333 (PC 2700) Notebook Memory - Retail