what are you planning to run on it?
for a dedicated server, it will cut out the graphics and focus on movements and physics. therefore a more powerful CPU would be far more useful than a powerful video card.
I would suggest just get a cheap video card, maybe a 6200 PCI-E or FX-5200 AGP, and use the money for a better CPU and/or more RAM
G.Skill makes the fastest RAM so far, look for some with Samsung TCCD's
also, if you can afford it, go for a dual core Athlon 64. they are in 4200+, 4400+, 4600+ and 4800+
you might need to look around for a motherboard that supports dual cores. if you have to update the BIOS, it should still run on one of the 2 cores before the update, so you won't have to first use a single core CPU to update it.