Server Upgrade----cpu/mem?

[J.Christy]

I am curently running SRCDS on Windows Server 2003 with an AMD Duron 1400 with 256mb ram (pc133). Suprisingly it is running pretty well. (24.10.5.14) I am going to dump about $100 into it this month, and I would like to know where I can get the biggest performance boost from....upgraded CPU or more MEM? Eventually I will do both, but not right now. Motherboard is a socket A and I think it says it will support up to an athlon xp 2600. I would greatly appreciate any information on this. I can also support DDR2700 mem.

Thanks,

Jon