[Thomas An.]

For those using Trillian and hating it (mostly the fact that you have to pay for the pro version).
I have tried Pidgin, Digsby, and Miranda.
http://en.wikipedia.org/wiki/Miranda_IM

Miranda uses the least memory (about 12k) and it is only a 4.3mb installation (compared to 26mb for Trillian). It is the most lightweight. It is also the most customizable ! ... and it supports the most protocols (even more than Trillian --> http://en.wikipedia.org/wiki/Comparison ... ng_clients )

The download is the most stripped down basic version. If you want to soup it up, I suggest:

• Plugins
  1. tabsrmm, and
  2. Popup plus, and
  3. Modern Contact List
• Themes (for "Modern contact list")
  1. Aero Bliss mod 4, or
  2. xpkaqua
• Skin (for "Popup plus")
  1. Milk, or
  2. Vista Aero Glass

http://addons.miranda-im.org/
http://wiki.miranda-im.org/Customise