Hassan:
First, the WLSE is like any other server platform, so anywhere with a suitable environment (cool, decent power/UPS, connectivity) should be OK.
Regarding recommendations for how many APs and where to put 'em .... well, that's much tougher.
The only absolutely safe answer is that it will depend on the outcome of a good site survey.
There are so many variables for any given environment, and they are almost always different, that providing an answer can only be the result of pure speculation. What that usually means is guessing to the good side and overspecifying the solution.
Even then, there are some unknown factors that you can only get with a site survey (like interference .... channels used by your neighbors, multipath potential, dead spots & such).
If you are unfamiliar with how to do a good site survey, it would pay in the long run to hire someone that is. It certainly is an added expense up-front, but the ultimate deployment will be more likely to work to your/ your customer's expectations.
Once the system is up, you can make tweaks and adjustments according to the measurements reported on the WLSE, but the primary setup shouldn't be based on a "good guess."
The number of users per AP is also somewhat variable, depending on the type of applications and the expected traffic from each user.
I've seen thirty users as an absolute max, with as few as ten for heavy traffic use. Generally speaking, somewhere around twenty users per AP for common use would be a reasonable number.
If you have users or systems that will be using 802.11b, that number may be smaller, because the AP must make accommodation for using both 802.11b and 802.11g.
More details would help, but without a good site survey, noone can really give you a firm answer.
Good Luck
Scott
