That said, the MBA will suit you fine for what you need it for. I imagine you're going to be running HD movies to that monitor? I output to my HDTV full 1080p with no problem at all.
I would also consider the MBP 13 (or possibly the 15 - but I think it is overkill for what you need it for). It is a nice machine. A bit cheaper for the base model and a lot of the parts are upgradeable (such as if you decide to get more ram down the line, or swap out the HDD for SSD). Plus it comes stock with 500GB HDD compared to the stock 128GB on MBA. 128 is good, 256 is better, but load up just a few HD movies and you will already be scrambling around for disc space.
In the end, if you can, wait a couple more months. Refreshes should be announced at least for one or the other (or both) anytime now.