wireless n slower than wireless g?

Hey everyone,

This is what I have:

Linksys WRT150N router
Dell Notebook with Intel AGN adapter
Desktop with Encore USB Wireless N adapter

On G-only mode, both adapters get about 6Mbps download speed.

On Mixed or N-only, the laptop gets about 9Mbps download but the Encore USB goes down to 3Mbps.

Why would switching to N create almost twice as much bandwidth for my laptop and cut the bandwidth in half for my desktop? I'd like to keep it on N for transferring files between computers but I don't want to take such a big hit on the internet on my desktop. YES it makes a difference. I tried downloading nVidia drivers and the laptop downloads around 500Kps while the desktop downloads around 150kps. Switch back to G-only and they both download the file around 250kps.

FYI: I bought the Encore USB N adapter because Newegg had a deal on Black Friday for $20 and free shipping.

Could it be a driver issue on the USB?

wait, what? you mean set the network up as N-only? I've done that and I get the same results as "Mixed". I just don't understand why switching to "mixed" or "n-only" from G benefits my laptop N adapter but cripples my desktop N adapter. Do some adapters just play more nicely with different routers?

good to know, and, thanks. I couldn't pass up the Encore N adapter. $20? It actually works better on G than my Netgear WG111 usb adapter did. I was just hoping to get better results with the N. It's odd. I got great speeds with both last night before bed (8Mbps+) but today it's back to the same bizarre stuff. I'm using WPA2 security. Found out about that a while ago. All 3 are N 2.0 spec (firmware updates) so I guess it just comes down to the chipsets. I'm not gonna stress it too much. At least I'm getting better G out of my $20. Who knows? Maybe a new driver/firmware update will improve things. Thanks mate!