I'm curious about your specific issue as well as input anyone has on this as that's the wireless router I own.
For all my OS / Laptop configurations my network works fine. I don't think it's OS specific and I never install the drivers on my notebooks.
Here are some things to check (be sure let me know if any of these resolve your issue!)
Make sure you've input the WEP key in your OS X machine
Make sure your router doesn't filter acceptable machines by MAC Address (if it does turn if off, connect your macbook, and then lock the MAC addresses again to add it)
try upgrading the firmware on your router if you haven't in a while. Linksys has released about 3 new firmware installs since that model was first released. Make sure you're current!
Can you macbook connect to other wireless networks (like Panera Bread, or at a friend's house, or at a cafe?)
Hopefully this list of things to check will help you narrow down the issue. It definitely shouldn't be an issue with driver support on your laptop though since I've never had to do that for Windows or Ubuntu or Gentoo.
when I got my first mac with OS X (bondi blue) I ran a Belkin wireless usb adapter and it worked like a champ, then I updated to 10.2 and it never worked again, I tried about every adapter made and none work (I had many for my Tivo's) I ended up just wiring my whole house finally.. but until I did that I used a linksys wireless bridge and just plug a cat5 cable from the mac to the bridge... I'll be posting about this and many other things like it on my blog... check it out..
As stated above I have this exact router. I turned on my mac, configured it via the initial boot configuration and it found the router. I connected to it and I'm getting normal speeds from it that are comparable to what I get on my Windows XP laptop and my Ubuntu laptop.
So I'm not sure what the problems are that you're having, but it worked for me out of the box.
the WUSB11 is a usb wireless adapter, not a router, so I stick by my statement above. one way is to use a bridge (game adapter), or belly up to the bar for the apple card for it... I assume apple makes one, but then again I'm not a full time Apple guy.