My global max connections is at 4000, and my max connections per torrent is 1000. The router never crashes anymore, and I usually have at least 10+ torrents downloading at once, not to mention all my other finished torrents seeding. These numbers work fine for me, but you may have to further reduce them if there's other systems on the network running bittorrent or other P2P software requiring a lot of connections. You may even be able to raise it under some circumstances, but considering most torrents connect to less than 300 people, these numbers should be good even for avid bittorrent users.

Neophyte: I found that capping the maximum upload limit and limiting the number of upload slots per torrent will allow you much more breathing room when doing other things while running bittorrent. Too much upload speed and you will affect your download speeds. A good number is anywhere from 1/3 to 1/2 your maximum upload. For instance, my upload tops at about 60k, but I find that my browsing during torrenting, while still slower than without, is drastically reduced with a 25k max upload speed.