Which Mac, version of OS X and version of Windows 7 are we talking about?
You might be able to get away with a variant of the Winclone method described in the MR guide.
http://guides.macrumors.com/Extend_or_Resize_Boot_Camp_Partition
- Attach new external HDD to Mac
- Clone OS X to external HDD using CCC or similar tool.
- Backup Windows partition with Winclone to external HDD
- Boot OS X from external HDD
- Reformat internal HDD as single FAT32 partition (use MBR partition scheme if 32 bit W7 or if GPT is the problem with TrueCrypt).
- Restore Winclone partition over new FAT32 partition
Could work, but isn't that much easier than a reinstall.
Alternatively, if you have multiple drives or a lot of space on your OS X partition.
- Backup Windows partition on drive "A" with Winclone to OS X partition on drive "A" or external drive "B"
- Replace internal drive "A" with new drive "C", place drive "A" in an external enclosure
- Boot from drive "A" in external enclosure
- Restore Winclone image to internal drive "C"
B