Thanks for the feedback people. I'll look into those case fans, DDH and will check out the 500GB Samsung prices, Vlad. I might get a second, smaller HDD for the OS - we'll see after a chat with the lady and final pricing.
philzgr8 - points noted. In the past I've used Nvidia in workstations without a hitch. The debate between the 2 will run until the end of time

I think its a case of just picking one in your budget that is quiet and has the connections you need. If doesn't work - put it on ebay!