Stevenarm,
judging by my personal experience - SP2 gives you a bunch of useful things, but you have to be careful with it. I've installed it on my personal computer and on computers of company I work for. The general conclusion is that, like Volk359 said, it has some nice goodies inside, but sometimes breaks various things. Two examples - on my personal machine video driver went insane (ATI Radeon), and in my company on one of the computers modem refused to dial any numbers (which was a real problem, as we use this modem to transfer customer details to bank). For me, the reinstallation of driver worked, for company's machine only cure was removing SP2.
Try installing it, but monitor carefully your system for any strange hardware behaviours and be prepared for them. If something's wrong try reinstalling drivers. If it doesn't help, post your problem here, maybe someone has a sollution. If not - remove SP2. Anyway, on most machines I had installed it on everything was fine.