easy to do, its all open...
Im seriously thinking about upgrading this CPU(only) its a Athlon 3500+(single core) and I could put in a Athlon X2(Dual Core) for pretty cheep! wouldn't need anything else, the motherboard supports the dual core processor so... pop this one out and walla... dual core...
AMD Athlon 64 X2 4400+ Toledo 2.2GHz 2 x 1MB L2 Cache Socket 939 Dual Core Processor - OEM $198
I already have a nice aftermarket heatsink that wont be a problem.
Whenever I swapped it was generally in big leaps, which meant different sockets, including a switch from Intel to AMD. It also usually meant another video card since I went through VLB (remember that?), PCI, AGP and PCI-X. And memory, through FPM, EDO, SDRAM, DDR and DDR2.