Depends on how much you want to invest and what you are planning to do with it after you have upgraded it.
The bare minimum for me is:
- dual internal 3.5" floppy;
- 2 MB fastram;
- internal SCSI harddisk (any size);
- KS 1.3 or higher.
With the above config you have a very nice gaming rig, but it's not able to run the more demanding and/or 'recent' Amiga software. For this, you have to add:
- turbocard (the fastest you can get);
- more ram (preferably on turbocard);
- a flickerfixer and/or videocard;
- 2 MB chipmem;
- Kickstart 3.1.
With this, you can run OS3.9, a nice update to older Amiga OS versions (especially if you've only been used to OS1.x).
On top of that, you can also add more stuff like:
- networkcard (X-Surf?);
- soundcard (Delfina?);
- cd-romdrive/USB-card/whatever.
After that, you have a pretty much maxed out 2000. It will most likely cost you bigtime, though. You will have a very cool 2000, but it will still not be able to keep up with a current day pc...
All in all, it depends on the amount of money, time and effort you want to invest in maxing it out.
