User blog comment:Andronikos Leventis/EA changes System Requirements for TS3/@comment-6471409-20111022135818/@comment-26744861-20111022205623

They did that with TS2 as well. The base game started off requiring an 800Mhz CPU and by TS2:AL, it required a 1.8Ghz. Though I did test this on another computer which was 1.6Ghz and AL was still playable - it just loaded slower.

You can probably still play Pets with a GPU that the base game supports but you may have to scale back your graphical settings,