If you're having a problem with Network Manager it's likely a problem with the driver. Since it's been a few years then you're probably better off with sticking with the default unless you have a problem.
There are two ways to fix wireless problems in Linux. Fixing the driver or working around it.
As Dan Williams (who is one of the main developer's for network-manager) has chronicled in his blog, sometimes it takes a long time; there are many moving parts, the kernel, the applet, and talking to the manufacturer of the hardware (if they even care) and then getting all that shipped to users. This takes longer than working around the issue, but in the end is a more sustainable model and gets everyone better drivers in the end. Network Manager and WICD don't exactly have the same feature set yet. WICD tends to deal well with wireless and basic ethernet connectivity, but doesn't yet support VPNs, DSL, 3G/CDMA and many other features which are becoming more and more popular.
This isn't meant as a slight towards the WICD folks, it does help people get online and that's great, but fixing it all the way down the stack is a better overall for Linux. Bottom line is, you can choose whichever application you happen to prefer, but if NetworkManager works for you, sticking to the default is probably what will get you the best results in the long run, since you will be able to benefit from the other features if you end up needing them. Network Manager, as the default network tool in Ubuntu is also supported by the Ubuntu team.
The linux wireless project maintains a page of wireless cards and chipsets and what features they support, and is a good guide to supporting manufacturers that maintain good drivers.