While some of their conclusions are suspect (to me), Consumer Reports did some double blind testing of the various wine preservation systems about a year ago. Basically they noted that, over the course of a day or two, that nobody could tell a difference whether you just jammed the cork back in overnight or used some fancy Argon anaerobic preservation system -- both tasted good. And, for red wine, after a week, both tasted bad. So really the preservation technique doesn't matter.
White wine preserved much better than red (that is to say, for a lot longer), but the same findings held true -- that the fancy schmancy stuff didn't actually improve longevity.
Ah...Consumer Reports. Quit paying attention after they recommended the Hanimex Practika as a best buy.
Another vote for the Vacu-vin, inexpensive and does the job.