Microsoft released Vista Build 5536 to beta testers last week, but regular end-users can take their chances with the latest build as well. After the tremendous response generated by the initial availability of Vista Beta 2 to the public, Microsoft has decided to limit this pre-RC1 build of Vista to the first 100,000 downloads
If you want to see how sluggish your PC can run, grab the download from the official site. There have been a -lot- of bug fixes since the open beta was released, so you can feel a bit better about installing this one.