Hi Henry,
Windows 7 really works best with a minimum partition of 40Gigs. I'm not saying that it won't install into smaller partitions but for optimum use......
To either remove partitions or create new ones you could use 'Disk Management', found by opening the control panel, clicking on admin' Tools, Computer management, Storage and finally Disk management. check the screenshot so you know which page to look for:
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Once you've sorted your partitions, reboot into your bios and change the boot order to CD/DVD first and then boot from the 7 disk. You'll then be able to use the set up process the reformat the partition your going to use.
I forgot to mention that to change your partitions by either removing/adding them or changing size then right click the HDD/partition in question.