The following are a few of the tools I use for testing mobile sites on Windows 7, prior to testing on actual devices:
Opera Mobile Emulator
http://www.opera.com/developer/tools/mobile/
Emulates the behavior of the Opera browser under multiple devices such as various HTC, LG, Motorola, Nokia, Samsung, Sony Tablet, Amazon Kindle, and a few others. This is my testing tool of choice because it is easy to use, fast and a close representation of the mobile experience.