Tip: If you can't get your PC to recognise your Hero, use the supplied cable
This might sound obvious, but.....
I have had weeks of problems getting my laptop to detect my Hero when connected by USB cable. Windows XP said "Device not recognized". I even resorted to trashing windows because I suspected the USB drivers were corrupted in some manner, and they wouldn't re-install.
This was all the while using a generic mini USB cable.
Brainwave! - moving the HTC-supplied USB cable from the wall charger to use with my laptop, my phone was detected instantly.
Don't ask me why or how, but the other USB cable I use doesn't allow correct detection.
I hope this helps you, fellow droider, who has had the same problems.