I installed 64 Bit XP (SP1) :roll: a few days ago on a system with following config. Pentium2.66 512MB RAM 6200TC (128MB) PCI-E The experience has been mixed one...some good and some bad. I am just typing these as they come in mind. Not in any particular order. First good thing is the bragging rights. Not many people have 64 bit processors, leave alone 64 bit OS. But thats not much good...is it?? Also this system feels a tad faster. But I am not so sure. But the real trouble comes when you have to install software...specially drivers. Display drivers have to be 64 bit ( N'Vidia). Sound wont play untill some patches are installed. I have 8 channel onboard sound...but the drivers are 32 bit only...so they run in 32 bit compatibilty mode I have not installed modem till now. Dunno if 64 bit drivers have to be downloaded for that too. There are two Prgram files folders....one or 32 bit and the other for 64 bit software. Any software of 32 bit has a 32 written after it in the task manager. Also some software wont run..i get a message that the file is valid but for another type of OS (Huh). Compatibilty issues are present inspite of tall claims by vendors. Microsofts .Net,TweakUI and others like Java have to be 64 bit. Quite some pain downloading them considering that I dont have broad band. Some games like SilentHill4 wont run ....Message is that the game is not installed properly. Other games like Black&White in diagnostics would show the OS as incompatible...but would run fine. The OS gets detected as Windows Server2003...not as XP. Quite some tweaks like modifying start button text dont work here. Also you cant open explorer.exe in Resource hacker. Interestingly icon storage file...shell32.dll is still named shell32..not shell64 as I expected. Basically its same as in 32 bit. There are quite some other issues too..but I cant type them right now. May be later. You can install this OS if you like tinkering with your computer a lot. For casual or intermediate users...I'd suggest stick to 32 bit atleast for 6 months.....its not reallly smooth sailing as for now. Thats all .... Any questions or comments are welcome.