I have copied my all data from 320 gb HDD to my friend's laptop.. now I wanted to partition 320 gb & 75 gb Hdd..as both of them are empty now
Where did you install Windows 7?
Personally, if it was my setup, I would install Windows 7 on the 75Gb drive using the whole drive.
Windows 7 will only see and use 298Gb's out of the 320.
I would partition the 320Gb with 4 logical partitions as follows;
1st partition, 10Gb's for Page File
2nd partition, 96Gb's for pictures, videos, documents or whatever you choose.
3rd partition, 96Gb's, for whatever you choose.
4th partition 96Gb's, System Image and File Backups.
Again, this is how I would most likely set it up, the decision is ultimately yours of course.
There are a few great tools for partitioning hard drives, cloning, moving and re-sizing etc:
Free Partition Magic alternative & free Partition Manager Software for Windows PC, Workstation and Server - EaseUS. they have the free home version which works quite well and many people use it.
The other which I just came across recently from another post here, which is also free, has a few more options than EaseUS and works just as good.
Powerful partition manager and free for disk and partition management.
Hope this helps
Don