limneos

You partition size has somehow been decreased. Also, after installing Windows 7, a new partition of 200MB is created storing the boot records which is also the active partition.

You can enter Disk Management under Control Panel - Administrative Tools - Manage Computer - Storage , and see if you have any extra unallocated space. If so, you can resize your partition to use the maximum space available.

Now, if you want to delete the extra 200MB partition completely, I'm afraid you will have to run a repair from Vista DVD after that to fix the boot loader (you will need to manually set active your big partition, now the small one (200mb) is active(bootable))