Worksheet to calculate cost of rent vs. ownership

I just created a Yahoo group (see link at bottom right) so I could post an Excel file that I use when I'm checking out real estate. (If anyone knows of a better way to make this available via blogger, let me know!)
I set it up so I can enter various factors, including sale price, maintenance, tax deductibility, tax bracket, interest rate, salary and budget items, and it calculates monthly and yearly costs, tax savings, etc, and gives me a yes or no based on my savings goal. It assumes a 30-year fixed rate mortgage. Still a work in progress-- I'm trying to figure out a formula that would backtrack to generate how much I could afford to offer to meet my savings goal, if the seller's asking price is too much.

I have this saved up on my desktop computer, and it synchronises to my Palm via Documents to Go, so I can run the numbers while visiting apartments. Or for my own amusement while on the subway or whatever!