4965 adapter does support channel 13 on certain versions only based on the geo. From your message it seems that the adapter version you have is the one that has channel 13 disabled. If you can open up your platform and read the front sticker on the wireless card and write back, I will confirm if you have the right version.
Btwn, channels 1,5,9 are still overlapping. the only non overlapping channels in the 2.4Ghz spectrum are 1,6,11. Just FYI.