Usually a BIOS update ensures that you can keep goning up the processor list...
Dont assume that your motherboard will take the higest XP procesoor.
My motherboard i know (well via the site) will takea top of the range 3000XP but with a BIOS update.
It best to check to see what the top cpu it can take.
"ACR - ACR (advanced communication riser) slot, which competes with the Intel-developed CNR slot for riser card mindshare. The ACR slot looks like a PCI slot, except is offset slightly and flipped 180 degrees." Just look on click here