sorry for the late reply.
A budget-friendly board is generally made from budget components and therefore not OC-friendly. Please understand that if you want decent OC, dont get cheap motherboard. If you do, dont expect decent OC. You can correct me if I am wrong. However, this is the general rule.
AnandTech has good
reviews on socket 775 boards. I am sure you can find one that suits your needs well.
Celeron D has a lot of OC potential. (3GHz or more) However, unlike A64, you get a greater perfromance hit for using a divider. I think this has to do with A64's on-die memory controller, but I could be wrong. As a result, if you OC your Celeron D by a small margin (due to cheap motherboard) and use value ram (need to use divider), you might be better off not OCing.
I know I am madly biased towards more expensive motherboard. But the more I learn about OCing, the more I love high-end motherboards. You can see that I am fanatic and zealous about motherboard, can't you? :beer: