I have a laptop that came with 1Gb of DDR (Yes DDR 1 it's old) 333mhz memory. Recently I realized that both sticks were very corrupt, so I had to replace then with 256 MB of the same speed of memory scavenged from my broken Compaq, but my question is can I upgrade my ram to a higher speed? I know I can't upgrade to DDR 2 but will I be able to use 400 Mhz Ram? my computer is a Vaio FS 680W. Thanks in advance for any help.

Each memory slot can hold DDR PC2700 with a maximum of 512MB per slot, or a total of 1 GB. You can try DDR PC3200, or ddr PC4000, but it likely will not work. If Sony has posted an approved upgrade, I have not seen it.
The Sony VAIO motherboards are very persnickety.
There isn't much noticable speed difference in actual use between the PC2700 and the PC4000 anyway due to the Front Side Bus, and other hardware limitations.

I didn't know the max memory was 1Gb...I thought I read somewhere it was 2 so thanks for the tip.

please read the upgrading ram guide in the guides forum.