My buck two fifty...
From a User world, XP is pretty, easy to use, fast and game friendly. The fact that they really dressed up XP indicates they are headed for a new look. The fact that this "dress up" has been integrated with more very well done multimedia features is even better. XP, contrary to some, is a solid product, actually one of their best considering what the first few were like. It's automated dll's and vxd's find almost everything you put on your machine...automatically. It uses the Win2K optimised network engine, which is apparent in increased internet efficiency. Moreover, from a support standpoint, it now supports many more products than any of its predacessors.
In addition, it is a gamers dream, utilizing much better drivers than were available with win2k (a very deficient gaming platform but great for business) although you can always tweak em out with mfgr upgrades. Games play much faster, the multimedia as was mentioned works better than ever before and built in support for new hardware is excellent. I am not going into MS the conspiracy rumors or any of the other crap out there...I am stating facts. Facts from the gaming world and user industry.
Now, for business...Windows 2000 or 2003 wins hands down and should be the base platform for your place of work if they use MS. The 2000 platform is stable, integrally supports Exchange servers, optimizes internet access and supports Active Directory much better than any other platform. The integral tools along with supported third party products make is a key platform in the enterprise enviroment.
Yes, I support Micrsoft servers for customers, thosands of them in a multi-customer business for one of the largest corps in the world. I am speaking from 28+ years experience in the computer hardware and software field, where I witnessed first hand the birth of the PC and the death of distributed computing. Not only am I certified on many products from Lotus to MS to IBM, but I have had work experience in them for many years. So I am speaking from experience when I say the MS products, while filled with their share of problems, do work and perform well in their perspective environments. OH, and no, I don't work for MS!
As far as SP2 goes, Milo made a good point on the integral firewall. There were several features that were quickly judged by the masses as problems when they ere only configuration errors. I think for this reason, along with some valid ones I am sure, SP2 was given a bad rap from the start. Now, I will tell you that I am not as well versed on XP as the other products, but believe if configured correctly, it will work fine. Probably the biggest mistake I see is IT professionals ordering laptops or workstations with XP. It works fine in the environment, but win2k products are better imho. What I want to see is other IT professionals oppinions on the products. Nothing against our younger audience, but unless your work with and support it for a living or are quoting an IT site, it just doesn't hold the value in this discussion. I would like to see more facts myself...that way we can better answer the initial question of this post.
Enough ranting...whew...now I must get back to my servers.
Carl