It seems that customer reviews of these things (PCIe wireless N adapters) can be very hit or miss. I think this might have to do with the fact that even though wireless N has a greater advertised range and speeds, the protocol itself can be more finicky with interference/obstacles causing more dropped/intermittent connections to the router on average.
The one design "flaw" with these PCIe N adapter cards is that the antennae are positioned so they stick out of the back of a (normally) mostly steel PC case, and therefore are likely prone to shielding. As a result, I've heard people report better luck (more consistent connections) with the recent wireless N USB dongles than the PCIe cards.
In light of this, I'd recommend looking at something like the Trendnet TL-WN822N
. You get a beefier antenna then what normally comes with a USB dongle, yet you can use a rear USB port and have more placement flexibility to get the best signal possible. Plus, you don't end up using up a PCIe slot.