It “should” be. I’m not an expert on that specific equipment, but a .11G AP should be able to support .11B Clients. The first catch is that .11b clients will be slower than .11g clients. See searchmobilecomputing.com for a lot of information (I found one article going in to login: http://searchmobilecomputing.techtarget.com/tip/1,289483,sid40_gci1116650,00.html?bucket=ETA
that might be a direct answer.