Slow file transfer over home network

I am trying to copy some files wirelessly over my home network, but it seems a bit slower than it should be. The two computers are running Windows 7, the router is a 54G Linksys (WRT54G), and I am connected using the wireless G mode. Both computers report 'Excellent' for the wireless signal strenth. When copying the files, the speed reported in the copy status window is around 1.2MB/s. Shouldn't it be faster than this? Yes, I know 54 Mbps is not the same as 54 MB/s. 54 Mbps is theoretically 6.75 MB/s, so it seems like I should be hitting at least 3-5 MB/s. Any ideas what could be causing the slowdown and how to fix this?

P.S. Before anyone suggests disabling the AV software, I am using Microsoft Security Essentials and I don't think that would be the problem.

 

try another channel?
is that speed on one latge file or several small?
expect 2.5-3.0MB/sec at best over G

 

The average transfer rate for the WRT54G is 22 Mb/s due to error rate and relative distance to the router. WAN to WAN transfers are however close to half this.