First off, I'll say I'm successfully using PDANet on my Win 7 laptop with my Sprint EVO. Composing this post with it, in fact.
Initially, I was having problems getting my laptops (XP and win 7) to recognize my Evo. "Unrecognized Device" or something like that.
Downloaded the HTC/Sprint sync software hoping that would install an appropriate USB driver...but the sync software wouldn't work at all. It should work fine on Win 7 (professional in my case). Then I started looking around the net for ideas. One chap recommended trying a different USB cable...so I did. Went back to the HTC cable instead of the cheapo generic one I bought on ebay. Instant success and no failures since.
APPARENTLY, SOME OF THE CHEAP MICRO USB CABLES are not fully compatible with the Evo (or possibly other devices). It seems to charge just fine on the laptop, but not so good for data transfer.
If your phone doesn't work on your laptop, try a REAL cable with the HTC sticker on it.