Without breaking the bank is a relative term really... depends how big your bank is....
It's also a matter of personal preference. I happen to like ATI cards because they've always caused me the least trouble.
The above spec 9600XT is pretty reasonable... It'd take you up to DirectX 9 functionality at a reasonable speed and relatively low cost. Basically go as fast as your budget can stand. Your next step after a 9600 is a 9800... After that, most of the ATI cards seem to be headding for being PCI Express rather than AGP.
That said, they have released the X800 on AGP as well, but I suspect that might fall into the breaking the bank catagory.
Best Regards,
Julian (Fozzy The Bear)