To help find sn's on which your relatively rare file is being uploaded:
Click on the "file" drop-down menu, clicking on "Extract SN IP's of dat file." Click on and open the file you wish to target for dl.
Check status on the list to find active supernodes, response times, location and switch to a SN with response time 0.
Not all rare files will come up with a list, but I used this method for finding SN's to dl T3. After a week of using my favorite sn's and random ones from the kazaa list, I stumbled on this area of the "file" menu. After connecting to sn's on this list, I was able to dl T3 in a couple of days. That's pretty slow for you folks who use bittorrent, etc, but pretty speedy for kazaa.