Update:

I've been using this build for a few hours now.  I did the upgrade as Microsoft suggested - direct from XP SP2.  I did a clean XPwSP2 install with my T40 DVD, before attempting the upgrade.  Took about 1.5-2 hrs on my T40.  ugh.

Anyway - with the exception of a few glitches during setup (very minor, like the SAT not running properly) - all seems good.

Previous builds resulted in a slower computer for me - but this time, my system is running like it did in XP, except now with nice searching features, and a nicer UI.  I still wish my video card worked EXACTLY as it did in XP - there's no real excuse for this, IMO.

So far, so good.  Quite a nice build.

Update 2:

StarCraft works.  Skype works better.  All my programs work, except Daemon-Tools.  And I mean, EVERYTHING.  I've wiped XP off my other partition and I'm using this exclusively.

I still have Windows 2003R2 for testing/development, of course.

Unless there are some serious regressions, build 5536 onwards should be very usable, even for the average joe.  I think it all boils down to the driver support.  There are a few pesky annoyances - but nothing BREAKS, other than the drivers.

Give it a try, if you can.  You shouldn't regret it.  My current install is an UPGRADE from XP SP2, and I'm REALLY impressed.

This is an x86 release ONLY.  An x64 build will not be available.

We are pleased to announce the release of Pre-RC1 build 5536.16385!  This build represents significant progress incorporating your Beta 2 and 5472 feedback.  We ask that you please download, burn and install a copy of this build as soon as possible.  Immediately afterwards we ask that you report any problems you encounter.
Upgrade!
 
If you have the time, please install Windows XP Professional or Home and upgrade.  This is the preferred test path for this build.  If you cannot upgrade from XPSP2 then clean installs or upgrades from Beta 2 X86 are OK too.  Upgrades from any other X86 build are not supported, not of interest to us, and should not be performed.

In general, the order of importance is as follows:
 
1.       Install/upgrade blocking bugs
2.       Stability/Security/Reliability bugs
3.       "Self-host" blockers - issues that prevent you from using the system as a primary OS
4.       Leaks and critical app/device problems
5.       New problems you notice in this build
6.       Regressions / things marked as fixed, but are happening again
7.       ANYTHING with a bluescreen / memory dump!  Even if you aren't sure what you did - bug it anyway.  Please title those bugs with the phrase Bugcheck:  in front of your bug title.
8.       Please focus on bugs that meet the above criteria until Tuesday, August 29th so that we can focus on these most critical issues first.

Direct Microsoft Connect Link to X86 release: (login obviously required)
https://connect.microsoft.com/windows/Downloads/DownloadDetails.aspx?DownloadID=2789