From my personal experience, if you are going to run a wireless LAN, find a different phone other than 2.4Ghz. The still make some very good 900Mhz phones and you wont have to deal with problems that may or may not arise from interference.
At work we just got done testing a CISCO Wireless Access Point that ran at 2.4Ghz, and the problems with interference were numerous. Everything from the WAP shutting itself down to data corruption.