I have DSL as well and a Firewall. I usually leave Limewire up and running most of the day.

When I am actively searching and downloading I will cut off all uploading from my machine (Setting Bandwidth to 0% and Uploads to 0) until I have completed my session.

When I am done then I set things back to normal. My normal settings are:

Bandwidth : 25%
Simultaneous Uploads: 4
Uploads per Person: 1

I also block freeloaders and classify a freeloader as anyone sharing less than 25 files.

I hope this helps!