Does she absolutly NEED this specific program? Something with that many dependencies sounds iffy to me. There may be better open source alternatives to whatever she is doing. I have dealth with many software packages and from experience anything PC based that really can only run on one specific OS tends to be shitty.
http://en.wikipedia.org/wiki/Categor...gement_systems
That being said, you are working with microsoft, not linux. A weakness of M$ is that when you have dependancy problems they are often built into the system in a way that they cannot be fixed
and this is by design. I am not familiar with MDAC, so there may be a workaround, but my simple bet would be to Dualboot XP and Windows 7.
DO NOT TRY TO INSTALL WIN XP ON AN EXTERNAL HARDDRIVE. IT IS A NIGHTMARE. Not that it can't be done, it's just that WinXP is designed to hate you when you try to do that.