Download speed slower than upload speed

I am getting very slow download speeds on my wireless router (Linksys model#WRT160N). I measured it on speedtest.net. with my ASUS laptop, ASUS Transformer Prime tablet, and 2 Ipod touches. All similar speeds.

Download avg: 1.30 Mbps
upload avg: 6.20 Mbps

I measured my desktop speed that is hardwired through the router to the modem.

Download avg: 30.00 Mbps
upload ave: 6.20 Mbps

I have scanned all the wireless connection in my area and found them to occupy channels 1, 6, 11. I tried changing my channels one at a time for all 11 channels. Some did a little better than others but not a lot.

Any ideas what can be causing this?

Also, if I by a dual channel router, can all wireless devices pick up on the 5GHz spectrim and if some, could this alleviate some interference?

Is it possible that my router is going bad and a new single channel 2.4 GHz router will be fine?

I am having the exact same issue. Download speed of .5 Mbps Upload of 3.5 Mbps. Direct connection tests fine. Did you ever figure it out?