Totally depends...purey from a "design" perspective, the
3000 was overall superior. However, even if you only
plan on running WB apps, the bandwidth of AGA will make
the 4000 far nicer to work with.
As far as upgrading, the costs are ultimately the same,
except you can probably get away with not towering a
4000.
--edit
Personally?? I'd take the 4000 over the 3000, unless it was a 3000+.
If you plan on spending a lot to upgrade it, and don't need AGA,
get whatever's cheaper.