Hmmm... Well, an A4000 would be a nice option, but you've already put a lot into your machine. Using the native graphics is gonna yeild similar performance on a 4000 with an 040/28, so right now your best option I'd say would be to get a graphics card of some kind. Absolutely essential add-ons for any Amiga:
1) Hard Drive
2) 040 CPU or greater
3) Graphics Card
A graphics card make such a difference to my machine (Also a custom-towered A1200) that I can't beat to use the AGA modes, even on 16 colour. You won't regret it, trust me!
