Need some advice on acoustic treatment

[No name]

Well, we've moved. I've got all my things moved into a room down in the basement (PC, midi controller,etc) i'm gonna go ahead with the task of doing a little acoustic treatment. This rooms needs it quite badly as it sounds rather boxy at the moment. I think one reason may be because half way on the ceiling the ceiling drops down about a foot and there is a big pocket going all across the ceilings, i'm positice those high freq are getting trapped up in there cause I can still here that echo when I clap. Anyways, now that i've quite smoking and all i've saved up the moneyt and can now buy some diffusors,absorbers and traps. I wanted to ask if anyone knew of a way I could test the room for resonant frequencies. Say, a tone generator program for the pc or something. i'm gonna add the dimensions of the room in case anyone wants to check it out and offer some advice. Thanks!

[birrbits]

heres something fun:
http://www.realtraps.com/modecalc.htm

and a good article here:
http://www.ethanwiner.com/acoustics.html