The following utilities may help you. They are freeware and they work on Windows 7.
Process Tamer is a tiny (140k) and
super efficient utility for Microsoft
Windows XP/2K/NT/Vista/Win7 that runs
in your system tray and constantly
monitors the cpu usage of other
processes. When it sees a process that
is overloading your cpu, it reduces
the priority of that process
temporarily, until its cpu usage
returns to a reasonable level.
Process Lasso is a unique new
technology that will improve your PC's
responsiveness and stability during
periods of high CPU load. Windows, by
design, allows programs to monopolize
your CPU without restraint -- leading
to freezes, hangs, and micro-lags.
Process Lasso's ProBalance (Process
Balance) technology intelligently
adjusts the priorities of running
programs so that badly behaved
processes won't negatively impact the
responsiveness of your PC.