Dell is going private at $13.65 per share, so why is it trading at $13.95 per share right now? Does anybody know when the buyout will actually go through? I can't seem to find that information anywhere.
Dividends would be a possible factor you are ignoring. If Dell has another quarter or two to pay out dividends that could account for some of the difference there.
I don't think there is a confirmed date of when the deal is done yet other than around the end of Dell's second quarter which was in the LA Times link you cited.
There is also the potential for the terms of the deal to be revised that is another possibility here. Have you examined other deals where a public company went private to see how the stock performed in the last few months before the deal closed?