A friend of mine that works in the IT industry just stunned me by asking whether there was anything new in SP2 for Windows XP - seems we haven't quite got the message out there enough yet - be prepared for this one, it is not just another Service Pack.
So, for him and you, I've linked the Microsoft.com page that conveniently lists the resources available for SP2 for IT Pros:
Developer-focused info is here: http://msdn.microsoft.com/security/productinfo/xpsp2/default.aspx
I don't care what anyone else tells you - in my opinion, this is Windows XP - The Second Coming. It's a pretty major product upgrade, and you need to have at least a rough idea of what's happening in it if your professional life intersects with it.
Why won't they put in tabbed browsing?
I had high hopes for SP2 RC. However, I installed it on my laptop, which is relatively pristine. What a mess! Completely hosed multiple networking features and slow as a unstuck pig. Also, personal firewalls are a PIA, esp. those that manage outbound connections. The old ICF was fine; I don't click on the email attachments and I have an AV on the box and I don't visit hacker or warez sites, so the new ICF is just a barrier. Blah! I'll give SP2 RTM a shot, but if its as nasty as SP2 RC, I leave it up to the unwashed to punish themselves with it :-)
My home machine also rejected XPSP2, though it's not slow. The machine's kinda passive-aggressive about it - the Firewall simply doesn't work when it's installed. I spent a whole four minutes trying to troubleshoot it, but didn't press the issue and rolled back (I've tried it thrice with the same result). My home machine is quite "fresh" in most respects.
On my relatively gunked up work machine, it all works beautifully, natch.
Anyway, I was going to say - I think that given the current threat landscape, it's critical that end-users are protected from doing Harmful Things. I spend the odd weekend cleaning spyware from a relative's PC, then explaining how it got there and how not to get it again, but I think we (as Microsoft) have a responsibility to help ensure that they get it right without needing to be taught.
I think SP2 is the Right Move; we're doing everything we can to get the RTM right.