So just boot into Linux single user mode on the Rescue disk. Get root shell, and at # prompt, type fdisk on the linux disk (if you have 2.6 kernel, ls /dev/disk/by-id/* shows you your hard disks), delete all 0x82 & 0x83 partitions, any Linux RAID partitons or Linux Logical Volume Manager stuff. Write the partition table, making sure you have not deleted any MS stuff, and that the partition number of all MS OS partitions is not altered.
Then use MS Utility to resize the C: drive (included in Vista) perhaps something like Partition Magic, which isn't expensive compared to most MS software.