I have the same problem on my machine (XP PRO) but it installs fine on my wife's computer (XP Home).
According to the Lucasarts website they are aware of the issue and are working on a fix.
"At this stage I believe I now understand the truth, which is that Lucas has gone over to the dark side. He is a Darth Billionaire ruling an empire, and is no longer leading a rebellion. He was once a semi-independent force, overshadowed by a dark and powerful business, but still managed to beat the odds and on his own terms, but now he sits on a throne with lightning in his hands and a franchise in his clenched fist."