Broadcom's bcm4318 should work just fine with the included b43 kernel module -- all you need is the "firmware files" which you get using a Windows driver and a b43-fwcutter. To make things easier this is all done with a few clicks
at least in the latest 8.04 version - and I'm pretty sure also in 7.10.
Ndiswrapper surely works, but it _is_ a pain to install every time you make some changes. The b43 module is easier because it's already there and after putting the firmware files to /lib/firmware it works happily ever after - you can even copy the firmware files and after a reinstallation just copy them back, provided that the b43 module isn't upgraded too much - or just re-run the graphical tool and have it work in a moment (this of course requires internet connection).
The trick is to launch Restricted Drivers Manager from the menu. The tool ought to find your bcm43xx wireless card and allow you to select it to be enabled - it asks if you'd like it to find the needed stuff for it from the web, and after answering it installs fwcutter, gets the driver files, cuts them and then the module should work. Last time I tried it installed the needed things and I was on air in less than a minute, with three or four mouse clicks (and I didn't have to manually download anything).
There used to be bcm43xx module in the older Ubuntu kernels that did the same (but with bcm43xx-fwcutter), but as far as I can tell, b43 (the newer one) works at least as well or maybe even better than bcm43xx. Resorting to ndiswrapper just makes things worse.
Note that Restricted Drivers Manager is a Ubuntu-specific tool, and what it basically does is be a front-end to some other tools that locate hardware from your machine that require proprietary (or non-open-source) drivers, try to locate the proprietary drivers from the web (reposity) and install them - nVidia or ATI graphics card drivers, bcm43xx wireless drivers, some winmodem drivers - which basically means doing the same steps the user would need to do, but automatically (for example download driver, fwcutter, use it on the driver, copy files to /lib/firmware, load kernel module, ...)