Hey Craig,

For the dedicated server I've had a standard one though I've not really put it through it's paces to know if you'd need a better one. It's been fine for me the whole time I've had it though.

For split testing, I'm a big fan of just using Google's website optimizer which you can get through your Adwords account.

If you're getting a decent amount of traffic, you could easily set up a multivariate test and let Google keep track of everything for you. They also make it very easy to analyse the results - "Green" means improvement, "Red" means worse performance

I have this up and running on a few sites. The great thing is that Google wont give you a definitive result until the test is statistically valid - a lot of people using regular split testing seem to forget this point and can end up making a judgement too soon.

Hope this helps,

Richard