Wireless in Ubuntu 10.10 is bad. Pitifully bad...
There is a bug somewhere in it that causes massive amounts of lost packets, but none of the developers will acknowledge it exists as it's somewhat elusive to track down and replicate.
The easiest way around it is to use the Windows XP drivers for your wireless card.
Install the "Windows Wireless Drivers" package through the normal software center. That gives you a new Administration entry for Windows Wireless Drivers. Load that tool, then point it to the .INF file for your network drivers.
That will convert the Windows drivers into a kernel module and your system will start using that instead of the normal Linux drivers.
You may need to reboot in order for it to take full effect.
You should notice it being a bit more stable after that.