Shareaza is deffiently the way to go, expacially if your gonna download torrents. Shareaza has a scheduler wich lets u tell it how much bandwith u want to be going in or out at what time, THIS IS VERY IMPORTANT if your using a cable connection, because u will have to upload while downloading and if u have a constast upload of 150kbs for over a certain amount of time, ur modem will be capped to a lower speed.
Long story short being able to set a schedule helps keep u from losing speed. I set mine for full speed one hour, limit 50% the next, full again, and then no speed at all. THen repeat that order. This will keep u download and uploading at top notch. I can dl 1.1mbps at my best and upload 800kbps on my best.