This might not happen if you remove the drive letter assignment from XP partition when in Win 7.
If Win 7 won't let you (which will happen if your Win7 boot files are on the XP partition), or maybe you want to access data on the XP partition from Win 7, then you either
(a) live with it
(b) use a different drive image product. There are many to choose from, some with a free version - although possibly more limited in capability.
My advice would be to ignore Acronis, btw - used to be market leader, has since fallen in a swamp and is liable to drown you. Check out this site where a lot of knowledgeable discussion about the whole subject goes on
http://www.wilderssecurity.com/forumdisplay.php?f=97
On there, is a discussion that the built-in windows backup is a dud anyway - no future, no compression, no.......quite a long list
www.wilderssecurity.com/showthread.php?t=350601
For a dual-boot system (I have the same myself), an excellent solution is BootItBM which includes bundled partition management and DOS drive imaging (I bought the speciall bundle, includes Image for Windows as well).
http://www.terabyteunlimited.com/index.htm With that you can have a multi-boot setup which installs automatically, hides the drives you don't want to see, and gives you all the drive imaging you might want also, with or without rebooting. It's consequently a little more complex than say Macrium or Paragon once you go beyond the automatic basics.
