In that case, I'd advise you to reinstall W7 from scratch, using the "custom" option at the start to reformat and reuse the space taken by the previous Vista and W7 partitions as one large primary.
What you are trying to do in converting W7 to a primary, merging it with another partition and destroying the integrity of the BCD by moving the start point, is not something to contemplate if you are not a confident and experienced user.
You will certainly need to acquire a W7-compatible Partition Manager, and to create a W7 repair disc (Control Panel > Backup > Create System repair disc) before you start.