Nforce would be your best choice, as it's the best integrated video around for the Athlon.
Newegg has the A7N266-VM for $71 new, but its a mATX board and its based on the 220D chipset rather than the better (dual-channel) 420D chipset. However, if you only have 1 stick of DDR you won't be able to use dual-channel anyway so it won't matter.
Another option that you would need to jump on right away; newegg also has an MSI K7N420 Pro refurb for $65. That's probably your best option if you manage to snag it before the refurbs are gone.
You could also try the KM266 chipset, your 3D performance won't be as good and these are all micro ATX boards but newegg has a lot of them. Just run a search for KM266, they're all under $80 new.
I think that pretty much sums up your options.