I am running Linux Mint, version Julia.
I have an internal wifi card that runs the 'g' standard. Most of the time it runs fine but sometimes it is not able to connect to my router.
I purchased a netgear WNDA3100(v2) ('n' standard) usb dongle and use ndsiwrapper to get the driver loaded. I now have two ways to get to my router and can switch between the two. The WNDA3100 can see my router but can't connect to it. It will try for about a minute and then give up. I have both set to the same WEP security. If I re-boot into Windows, both can access the internet.
When I right click on the network icon in the bottom try and chose 'edit connections', the only wireless connection I have, 'home' was last used - never.
Any ideas?

TIA

Can you post some more information on your Wifi cards? Chipset data is really what we need. Run these commands and post the output:
Also, remember that NDISWrapper is a last resort in terms of functionality. It basically stuffs Windows drivers into the Linux kernel and hopes for the best. Functionality issues and instability are often problems with NDISWrapper, and usually cannot be solved very easily.

john@Desktop ~ $ lspci | grep 802
01:0a.0 Ethernet controller: Atheros Communications Inc. AR2413 802.11bg NIC (rev 01)
john@Desktop ~ $ lsusb | grep 802
Bus 001 Device 009: ID 0846:9011 NetGear, Inc. WNDA3100(v2) 802.11n

Are you running the latest ath5k drivers? Atheros chips generally have a very good reputation for linux compatability.

As for your netgear card, I'm not seeing much info on it. I would suggest in the future to look up any wireless card before you buy it and check compatability with linux. It's really touch and go with wifi chips, even within the same vendor.