I still think it should be a 1492 as well. The reason the MSS is 1460 in both, is because there is almost no difference in a mtu of 1492 nad 1496.
this is what i used to make those files http://www.j79zlr.com/cablenutXP2k.php
that second result is cached, clear it and try it again.
It could be the router, but its most likely your computer, or something interfering with the wireless connection. what kinda wireless card do you have on your computer, and do you know approximately how far you are from the router.
download the newest TCP optimazer from here http://www.testmy.net/forum/t-11975
and make is look like the attached picture. save the changes and restart, then post a speed test.
who is your ISP?
and try this test http://www.testmy.net/tools/test/d_load.php?step1_timed=&step1_size=&step1_validation=&testall=&s=12160&st=st&ni=ni&ta=&top=&tt=1&nobar=
also have you done any tweaks on your connection yet?