I have a VacuVin, which works fine if I'm expecting to have a bottle open for >48 hours or so. If I'm going to drink the rest within around a day of opening, though, I just reinsert the cork, or put in the VacuVin stopper without pumping out the air. I have this notion that reducing the pressure of air in the bottle will tend to increase the vapour pressure of the wine in the bottle, and that will encourage the more volatile compounds to evaporate, to the detriment of flavour. No idea if that actually happens in practice, but it seems logical to me, so I'd only use the VacuVin with the pump when the bottle was going to be open for ~72 hours or more.
Edit, and wouldn't expect a VacuVinned bottle to remain good for a week: 4-5 days would be my working limit.