Do I risk corrupting a program if I end-task it?

----^----
---/|\---
----|----

Well, if it happens to be accessing a resource that is not completely internal (file, network connection, etc), then there could be corruption of that data, but you can't corrupt your application is you end-task it (assuming it wasn't rewriting itself or something to that effect).

I'm not entirely sure if I answered your question. Please elaborate if I did not.

Cheers

Yes, that awnsered my question. But I have a different one as well:
What if a program was running when the computer shut down due to a power surge?

nothing should happen, windows software is designed to fix errors after an unexpected shutdown, if your running 98 or lower, than the usual blue screen scanning for errors should run, but 2000 and above keep the system from program errors that may interfere with the boot up, unless there is a virus.

Same deal. If you were writing to a file or something, there may be issues with your file.

Cheers