If you cannot pause live TV, you need to get a DVR and join us in the 21st century. Of course, I say this as someone who still has neither an MP3 player nor a navigation device.
The TV interface built into Windows XP MCE, Windows Vista, and Windows 7 is outstanding. As long as you have a TV tuner, it functions better than a TiVO without monthly charges. Best of all, with a plugin called ShowAnalyzer, you can automatically skip the commercials without pressing a button. I haven't watched a commercial in quite some time.