Welcome to the forum, Rickajho.
Any particular reason not to install Linux on it? W2k Pro is
getting a bit long in the tooth, see http://support.microsoft.com/gp/lifean35
. Quoting the relevant part:
On July 13, 2010, Extended Support for Windows 2000 Professional will end. The product will no longer be publicly supported after this date.
64bit Linux client v7 supports Fermi and newer NVidia GPUs natively (core_17). With a 32bit Linux, the Work Units you'd get to crunch would be more restricted, but you could run a 32bit Windows NVidia GPU client v6.41 and core_15 WUs through WINE. While that isn't officially supported, IMHO setting it up isn't overly complicated.
Up to a GTX 460 level NVidia GPU, your points production would actually be better with the older core_15 work than with core_17. Even a slow CPU and a motherboard with a PCIE v1.x slot would be capable of keeping a moderately powerful GPU fully occupied, and some people have even extended the serviceable life of legacy PCI non-e
mobos and CPUs by folding on a PCI GT430 GPU. With an overclock to ~900MHz, they've reported as much as 6000 Points Per Day.
Most likely you'd get many times the PPD compared to folding on the CPU. In fact, aforementioned people rarely bother to fold with the CPU, they just use it to feed the GPU. There still are legacy (uni)core_78 WUs around, but without the Quick Return Bonus points, those aren't particularly attractive to most donors due to the poor PPD/Watt ratio.