Sims 2 doesn't seem to like dual core chips, will only use up to 4 Gigs of RAM. (Some say 2 Gigs).
Right click on the Sims 2 Desktop Icon (whatever you click to start game).
Then select PROPERTIES
Then in the target box type -w outside of the right " with a space. " -w so your startup target line should read something like
"C:\Program Files\EA GAMES\The Sims 2 Mansion and Garden Stuff\TSBin\Sims2EP9.exe" -w
Then you can minimize the window if you need to tab out, you can see your toolbar and clock, see if an IM, email or Skype comes in, track Sims using a spreadsheet, make notes about storylines, or use an external screencap program.
Edge scrolling doesn't work but use the arrow keys to move or right-click on a spot to go there.