dirkz - 10:26 am on Sep 12, 2003 (gmt 0) So my educated guess would be you to reach a PR7.
from my experience Google will tolerate "unrelatedness" to a certain degree, and this degree goes very far. I have done that in the past with very unrelated sites, and I'm still benefitting in form of PR. What I found in my example is (very roughly): A PRX page linking to you will gain you somewhere at PR(X-1), if you were PR0 and there are not many more links on the the linking page. Since the gaps in real PR betwenn PRX and PR(X-1) can be huge (especially in X greater than 4), ymmv.
So my educated guess would be you to reach a PR7.