It is absolutely incredible. iTunes for Windows keeps on getting worse! The UI improvements in iTunes 7 are welcome, but I just tried playing a 320x240 downloaded podcast, and it totally takes down my 2Ghz Core Duo IBM Thinkpad T60p. Incredible. In the little integrated video window, the podcast is choppy. Heaven forbid that you'd want to click on the video to bring it up in its own window. At default size, podcasts run at 2 frames per second, and audio filters in and out. I would have been really embarrassed to release a software product so crappy.
An anonymous iTunes development team member replied, "use the Mac version," when I brought up the extreme shittiness of the Windows version. Nice. :)
Update: I've gotten one of my other Windows boxes to play video smoothly using iTunes 7 for Windows. All I know is that on my Thinkpad, iTunes 6 worked, while iTunes 7 barfs on video.