According to what I can find on the specs of an IBM Thinkpad 600e, the bad news is that it looks like the 2.5 mb video is only part of the problem. The laptop doesn't meet the system requirements for The Sims 2.
The game requires a minimum of a 600 MHz P3 processor and 256 MB RAM. When a game says "minimum" it means the game will run on those specs but not necessarily run well. Full system requirements for The Sims 2 is on
this page.
The specs on a Thinkpad 600e I've been able to find says it has a 300 to 400 mhz P2 processor and comes stock with either 64 or 128 megs of RAM. If you haven't added RAM sinc eyou bought it, that will need to be upgraded to play the game, too.