Hmm here are my suggestions:
1. Do NOT go prescott no matter what the situation. There are always better CPUs for whatever price/performance range you need.
2. So you want either an easily replacable budget solution or a more future proof solution.
luckily that is a recent board with a very good chipset.
If all you want to get rid of is the CPU then simply buy a 2.4C ( note the C please
Amd Athlon-M 2500+
Asus A7n8x Deluxe ( i own this board and have no problems ever)
This chip is the mobile variant meant for laptops, MONSTER OC'ing ability.
If you cant find any nforce3-250 boards yet then a MSI 8KT Neo (MS-6702) should do.