To illustrate the point, I have a wireless network here. My internet is Telstra Cable.
Imac (plugged directly into router). 9.49 mb/s (800mb movie 11 minutes)
macbook (wireless N). 9.29 mb/s (800mb movie 11 minutes)
Iphone (Wireless G) 7.4 kb/s
As you can see there should be very little difference between wireless and wired for internet.
As to the PDA on wireless... maybe it's time to update

A $250 ipod touch has built in wireless.
All tests were done with speedtest.net. The test on the iphone was done with speedtest.net's iphone app.
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