I completely upgraded my pc lately after a crash. Windows 7-64 bit, I used to have Windows XP Pro. I noticed that when playing hd-movies on the 24'' screen the video slightly stutters. Not after just switching on the pc, but later on. Also seems that RealPlayer doesn't give these effects, while WMP does. It seems it just happens with hd-movies, not ordinary youtube clips. There could be several reasons. I've read that aero settings are consuming. My video camera software warns specifically for aero settings (and the pan views from that software are not smooth now). It could be the graphic card, Geforce 6600GT which is 7 years old and just has 128 MB memory. It worked okay with hd-movies in XP Pro, but maybe Win 7 64 and aero settings require much more memory? It could be overheating as the problem occurs after a while. Latest drivers installed on the graphic card but no changes. Anybody, any idea? I'm happy to buy a more powerful graphic card for my video editing later on, just want to be sure that this is the problem.