Bluetooth tethering not possible to PC Iphone4IOS4.2.1 Win7 64bit

Hi there,
Just got my first Iphone4 and have problems using the phone as a modem to connect my laptop to the internet. I have activated tethering and USB but the phone is unable to identify the laptop and therefore cannot pair the two devices. My phone company does support tethering and using the USB cable everything is fine.
I have just been informed by my phone company that thethering over bluetooth is NOT possible to a PC - only to a Mac. Is that really true? It seems ridiculous that you buy this beautifully designed phone and whenever you need to use the phone as a modem for your PC you need to attach a USB cable!!!
Anyone, can you use USB tethering on a PC with Iphone4 with IOS 4.2.1. If yes, please explain how.
TIA - new Iphoner
Lenovo W500 Windows 7 64Bit