Ok can you please advice me on how to do this.. since ive never done a hdd partion before.. also would i have to reinstall my programs when win 7 is realsed even though the files are still there ? or would they jusy show up in installed programs?
During the install process you should get an option to create partitions.
See here as an example in XP -
http://pcsupport.about.com/od/operatingsystems/ss/instxpclean1_10.htm
I'm sure Win7 will be very similar.
You will probably need to assign at least 30Gb to the partition which you want to install the OS onto. But you may need more space depending on how many programs you have, and how much space they require.
Once you have created the partitions, then each partition will show up in Windows as a different drive letter, eg c:\ and d:\, etc
The c:\ will contain the OS and I would also install any programs to here as well.
You can then use the other drives (partitions) for any files, such as documents, music files, photos, etc.
When you come to format and reinstall, then you can format the partition with the OS on, and all you lose is the OS and your programs. But all your Data Files are untouched and will still be there once you re-install an OS on the other partition.
Unfortunately you can't really keep Programs seperate (in the same way as you can for Data Files), because even if you install them on a seperate partition to the OS, they will almost always need to be re-installed once you reinstall the OS. So I tend to just keep the OS and Programs together on the same partition.