@PGit: I agree with koaftder - the only reason to get something other than a bog-standard machine is for gaming or for a specific purpose such as video editing. For either of these, the biggest and best graphics cards, RAM, hard drives, etc, are a must.
For everything else (including running an emulated Amiga), a basic machine will do. If you want convenience and portability, go for a laptop (downside = you'll pay more and probably end up with a slower hard drive), otherwise go for a standard desktop model.
Don't buy from the likes of PC World, Dixons, Currys, Comet, or any other high street shops as you'll pay more than you need to.
If you want known-brand peace of mind, go for something like a Dell machine. Alternatively, go for a trusted independant online retailer such as
Novatech. I used to use Novatech lots until I emigrated away from the UK.
- Ali