since you know relatively little about pc hardware, i would hold off to buy the AMD 64 processor. i would look into the XP2500+ and under CPU's and find a motherboard for those instead.
those are the best values right now. your 64FX chip would need a 64bit operating system that can take advantage of it, otherwise it isn't much faster than an XP3200 CPU for 32bit applications.
an XP2500+ will seem about twice as fast as your celeron processor at $92 including heatsink/ fan! all you need to do basically is buy a motherboard that supports amd processors and a 333mhz front side bus minimum, 400mhz recommended. for example: