Depends on if you plan to install the 32-bit or 64-bit version. The 32-bit version can be installed on about any computer that meets the minimum requirements, while the 64-bit version requires a 64-bit processor (which the Pentium M is NOT) in order to install.
I'd recommend running the Upgrade Advisor (available at http://windows.microsoft.com/en-US/windows/downloads/upgrade-advisor) to make sure your laptop can handle Windows 7.
Casey