Doesn't stop me and never has. I've gamed over Wireless for years now. Was on a PCI-E 54g internal card but I've now upgraded to a set of 5GHz Wireless bridges and have no issues.
if you have no option for an Ethernet cable then gaming over wireless is OK. Get an internal PCI-E card that supports 5GHz if your Router does. If not still get an N capable PCI-E or PCI card. USB dongles rarely work consistently in my opinion.
Will also add I get a consistent 4.4MB/Sec over Wireless which seems absolutely spot on for a 40 Meg Fibre connection.
Wireless has come along way regarding bandwidth speeds - this is typically how the new standards, routers etc are promoted. However in my experience it's typically latency and interference where they suffer. In saying that, it's been years since I've played around with wireless for my home PC.
Would you be able to perform a test between your wired and non wired connection using the following command?
Would be interested if you get much additional jitter between wireles vs wired on the same connection.