I used to use Handyswitcher but recently switched to wktask
http://soft.photoracer.net/docs/wktask_en.html because it's free and has better features. Both are light on memory and stable. I Tried SPB Pocketplus but like most SPB stuff, it's packaged with a whole array of unrelated features I don't need and a it's a bit of a memory hog. Being able to associate a button to switch tasks is the only feature I miss, but wktask's task bar icons are more useful. Think of wktask as all the most useful features of Wisbar Advance without the crashes and slowdowns!