[Dave Flowerday]

If this application is reasonably important (i.e. customers are paying for it and/or a company will suffer losses if it doesn't work), I would not recommend using Linksys or any other "comsumer grade" hardware.

I have a WRT54G myself and love it, but all of these devices at various times have had trouble with high traffic loads (yes, even with 3rd party firmware). In fact, I used my 54G to provide Internet access at Midwest with openwrt and an apparent memory leak would cause it to reset every 10-15 minutes since there were 100+ users connected.

Additionally, making indoor equipment ready for outdoor use is not as simple as sticking it in a waterproof case. Electronic devices are spec'd for certain temperature ranges etc. and if you use an indoor device you'll need cooling and/or heat in the enclosure depending on your location. Keeping humidity out is also a big challenge, as is dust (unless you fully seal it, but then the temperature problem gets worse).

Since you say money is not an issue, look for something designed for outdoor use. Motorola sells dual-radio outdoor hardware that has 802.11b/g and 802.11a all in one unit called HotZone Duo which also performs mesh networking (but it'll set you back quite a bit more than a Linksys). I'm sure you can find similar hardware from Cisco or other vendors. This stuff costs more for a reason, and it's not always just because there's a big-name label on it.