Let's summarize a few things:
1. A 1.8GHz G5 iMac is actually a very nice little computer, well worth what you paid for it. The only reason it's down in value these days is due to its age and the fact that newer Macs use Intel processors, which gives them additional flexibility and the ability to run newer software.
2. You can find out exactly what size screen you have by measuring it diagonally.
3. If you could find a CHEAP copy of Leopard, you could run most modern software AND keep the machine for a while longer. Check with your local Mac User Group -- there is quite likely to be someone who has upgraded to Snow Leopard who might have a copy they can give or sell you cheap. Be **SURE** to get a **RETAIL** copy of Leopard, not any "gray discs" (those are machine-specific and won't work for your machine).
4. You might also check to see if there are older versions of the software you want to use that works with Tiger (10.4.11). I know there is for Firefox.
5. If you do keep that machine, the only thing I'd say is really worth spending money on is RAM. You should max out the RAM on that machine, which I think is 2GB, and I think you'll find that it actually performs quite well.
Sorry you ended up with something not quite right for you. Hope things turn out okay. Next time you're thinking of buying a computer, check here first!
