How to Re-Size Partitions Without Losing Dual-Boot?

I had a dual-boot Win XP/Win 7 working successfully on my Inspiron 8600. Using Acronis Disk Director, I re-sized the partitions, after which the computer would not boot. After I recover the computer from backup to its original state, I'm going to need to do this again... so how can prevent my dual-boot set-up from being broken again?

Here's what happened the first time: in Disk Director, the disk partition structure looked like this: first a small FAT partition; then the NTFS Win XP partition; then the NTFS Win 7 partition. What I did in Disk Director was, first, decrease the size of the last partition (the Win 7 partition) from its front; so that I could extend the end of the Win XP partition to the right, into the unallocated space to recover it.

Thanks in advance for any help,