Hi,
1. Partition the disk before installing 7. If it detects an active partition, it will not try to create it's own 200mb one.
In other words, do not install 7 onto unallocated space.
Not sure of your current setup - you can partition with Vista Disk management and format it as NTFS, before installing 7.
Once you have a formatted partition, just click on during install to select it for 7 to install onto. ( Step 7 of the tutorial - do not select drive options advanced - click on the partition you see at that step and it will install there)
2. If you need to repartition during install , as you feel you have not set up the partitions to your liking in advance, select Drive options advanced, and recreate the partitions as you wish - make sure you format them before selecting one to install 7 on.
If you make a mistake and a box pops up asking about additional partitions for System files, click the Cancel button.
Clean Install Windows 7
Hope it helps
SIW2