You're specifying -border-radius:45px; ... it shouldn't have a leading dash. Not sure if that's the whole issue but it should be a start.
oops, that was a problem with my posting process, not the actual code. I had copy-pasted the relevant code into a text file earlier and while I was fiddling with PIE trying to get it to work, I realized it had that dash there and removed it from my actual code and proceeded to re-test it across the board. Then when I came here to post my question, I had already closed my remote css document and out of laziness used the version in my text file.
So anyway, I just went to look at my live code and confirmed the leading dash is not there. I also tried invoking PIE in a few other definitions in my css file and it doesn't seem to be working in any.
but as indicated earlier, border-radius.htc works ok... but it just won't handle anything other than rounded corners and I was greedily looking to get as much css3 yumminess for IE as I could.