Compatibility issue in Windows 7 Ultimate

[kRatOS1339]

i earlier installed windows 7 ultimate 32 bit but now i want to install 64 bit version. whenever i try to install the 64 bit version a compatibility error occurs but i know that i have all the things for the 64 bit coz i earlier installed it but now unable to install. plz help guyz!!!

 

[COLGeek]

There is no upgrade path from 32-bit to 64-bit Windows. You must boot from the 64-bit DVD and perform a full, clean install.

 

[kRatOS1339]

I tried that but when during installation the setup asks for a disk partitioned although theres a plenty of space available but when I click on any disk a message appears saying that windows was unable to find disk partition.

 

[COLGeek]

You have to reformat the HDD as part of the process (or select a new partition). You will not save any of your previous settings or files as part of the process. Just keep that in mind.