New Dell Studio 1745 - fresh install

Hello all, and greetings from a newbie to these forums.

A week ago I ordered a new Dell Studio 17 here in the UK.
Basically I have a 2 and a half year old Inspiron 1720 that I've used for iTunes, net surfing, and World of Warcraft, but the thing is now so damn glitchy I think there is nothing for it other than a complete wipe of the harddrive and a fresh install of Windows Vista. It refuses to install IE8 and SP2 and now the processor is completely clogged up with Vista trying desperately to get these downloads down. Every time I install them they download fine and then the computer shuts down, restarts, tries to finalise the installs, before saying "updates were not installed correctly, reverting changes". Tried turning off McAfee and a load of other things.
Banjaxxed my Warcraft time too as my fps in raids is now down to 2fps.

I thought that a new computer wouldn't be a bad idea before the 1720 completely dies, then I can wipe the Harddrive, reload the OS and sell the bugger!

So after much hunting through the net and electrical retailers I came to the new Dell Studio 17 because the deal Dell were running was significantly better than anything else available (better FSB, larger cache, faster DDR3 RAM, faster and bigger harddrive, and a 1GB ATi graphics - everything else had 512 max).
Now I have a delivery date of the 14th for it to arrive, but I was wondering whether I'll have to do a fresh install on it?

I've asked Dell to leave the bloatware off it, so hopefully I'll get Windows 7 (64 bit), McAfee, and the free Napster stuff (I don't use it because I have iTunes) and that'll be it.

Has anyone else received theirs yet, and is it in need of a fresh install prior to getting going? I'm only going to be playing Warcraft on mine so it should have mountains of processing power to spare, but I'd like to make sure it's going to work well.
Thanks for any advice you may have