I have just finished geting racechrono for PC woring under Windows 7 and thought I'd share some of the problems I had for the benifit of the community.
If your GPS receiver is listed on a double digit port number i.e COM10, racechrono will not work. I had to change my COM number allocation to a single digit port for it to work. I did this by following the instructions in this link: http://www.bisque.com/sc/forums/p/446/430.asp
I then uninstalled and re-installed the GPS USB to Serial drivers and the COM port changed to COM3 then racechrono was happy.
If racechrono can detect the GPS receiver but is not connecting to any satelites, you need to manually set the GPS baud rate. For my Sirf star 3 chipset GPS, the baud rate was 4800.
I also had an issue where racechrono would lock up when atempting to pause a session. This problem seeemd to disapear when I ran racechrono as an administrator. i.e. find the racechrono.exe then right click and select "run as an administratr" from the menu.
Hope this saves someone some time in the future....