Sorry to say Microsoft_Boy, but a majority of 'N' class routers don't function much better than their wireless G cousins, and vendors have various issues to iron out, according to various reviews I have seen...
Change the data rate mode to 802.11g only; change the preamble mode to short, change the channel/frequency to something other than the default. Disable DHCP; manually assign each computer IP addresses. If you have STP feature disable that also.
I don't recommend this but disable the security (encryption) will help a lot.