I guess if money is tight ...
Them the one best upgrade (imho) would
be a GFX card. But if you go that route make
sure you get a Zorro III card, not a Z2 card.
You can pick up a good card on EBay for usually
around $150.00 or less. IMHO that would be the
best single upgrade you can make.
If you want to install an accelerator then the
3.1 Roms are a must since all the good one
(I think) require 3.1 Roms.