As you can tell, you have not gotten a real responce.
There are some cards that can be recomended. I peronally have a CyberVision643D (CV643D). I haven't had any problems with it. It works in both ZII and ZIII mode (Zorro 2 and Zorro 3.). You can also get a GVP Spectrum Card. To be able to use any graphics card, you need to have a RTG system. I personally use Picasso96, but you can also use Cybergraphics. P96 uses the same API as Cyberygraphics, and P96 is going to be the official RTG (ReTargetable Graphics system) in AmigaOS 4.
BTW, the Amiga 2500 is nothing more than a Amiga 2000 with an accellerator card in it. It will only accept a Zorro II (Z2) card in it. As I said above, the CV643D card works in both, and you sould be able to find one on ebay.com for a low price.
And yes, you can have 256 colors, or thousands of colors, or millions of colors. I just depends on which resolution you work in.
