Something to note… if both machines are using wireless, your actual *speed* is approx. double (22mbps). Still pitiful, but at least that suggests it’s not some issue related to say, using a USB wireless adapter w/ a USB 1.1 port (also limited to 11mbps). The wireless router can only be communicating w/ one wireless client at any given time (i.e., it’s serialized). That cuts your throughput in HALF. So you either need to double your results, or limit wireless to only one client for testing purposes.
What 22mbps suggests to me is the possible presence of wireless G devices. Are there other wireless G devices around? Is the router in wireless N only mode? Are you using the second (+20MHz) wireless N channel?
Some older wireless N routers will slow ALL wireless speeds to the slowest supported protocol. More modern wireless N routers will slow the network only when those slower protocols are active.
While the latter is much preferred, you still suffer a total reduction in throughout the more wireless G clients are active since it takes longer for them to complete their transmissions, even though wireless N clients still perform at wireless N speeds.
That said, your performance results are so pitiful, it leads me to wonder if maybe you have one of these older (or a modern but el cheapo) wireless N routers that goes exclusively into wireless G mode as soon as wireless G clients are supported. It just seems a strange coincidence you’re getting what would be typical wireless G results (22mbps) under reasonably good conditions.