Um, I have to disagree with ez2remember. Nothing personal. If you're going to: game (as I guess you will by your handle), rip or burn CDs, do anything with video, or use web browsing features beyond mere HTML (Java, Microsoft VM, ActiveX), then you want the P4 2.4C. I think he might be comparing the XP2500 to the P4 2.4B. The 2.4C with hyperthreading enabled in WindowsXP is faster than the P4 2.66B, and in some cases the 2.8B.
No, synthetic benches aren't all that indicative. And P4 "B" chips are often outtperformed by AMD equivalents in tests. But the P4 "C" chips do indeed rock when paired with Canterwood and Springdale. As for the XP3200+ vs. the P4 3.2C, check out the brand new comparison at Tom's Hardware:
http://www6.tomshardware.com/cpu/20030623/index.html
The 3.2C WALLOPS the XP3200+. Tom's also gives the skinny on comparing the P4 C to the P4 B and AMD equivalents. Clearly no contest: the XP2500 doesn't beat the 2.4C in a single test, not even "real world" tests like PCMark and SysMark.
As far as Springdale vs Canterwood: the ONLY reasons you would want Canterwood are if you can't live without CSA (since not all Springs have it) or ECC. PAT is no longer an issue, since Intel left a "backdoor" to activating it that Asus let out of the bag and now most manufacturer's are exploiting via BIOS updates.
The Asus P4P800 is currently the "king-of-the-hill" in terms of Springdale performance. In fact, in a lot of cases, it the king of ALL performance, since it is faster than Canterwood boards from MOST manufacturers. And its cheap. (The P4P800 and 2.4C combo is what I'm using right now. I can send you some bench results if you want to see what it is capable of -- PM for those.)
ez2remember is right about heat, BTW. The P4C is hotter than an AMD. But keeping your SLK-800, in my view, would be a dumb reason to go with an AMD. The stock Intel cooler is pretty efficient (see MikeC's own review for that) and not terribly loud, so it works well as an interim. Personally, I'm using a Zalman CNPS6500-AlCu with the fan at about 8V, 2.4 OC'd to 2.65: 41C idle, 46C under load.
Hope that helps you clear the mud!
jamoore9