Why inflict VIA and their garbage chipsets upon yourselves? Sell your current motherboard and grab an nForce2 board. Even if you only get a budget single channel model you will notice the difference instantly.
Just recently changed my parents computer from KT133A, SB16 PCI, GF2MX400, 512MB SDRam, Duron 1.4Gig to my old Soltek K75MRN-L with integrated graphics and 1 512mb PC2700 DIMM, no PCI cards installed (everything else remained the same).
The speedup and increase in responsiveness/smoothness was obscene, especially when you consider the board isn't even operating in dual-channel mode and is utilizing the builtin graphics. Durons absolutely love the nForce2 chipset (the DASP works quite well for them due to the smaller L2 cache).