There are many legal ways to get a 'lite' version of Live which would likely suit your needs just fine and probably play fine on your existing lappy. Look for an audio interface or controller that has it bundled.

Many M-Audio products from a couple years back came bundled with some version of Live lite - even cheaper stuff like an Oxygen 49 keyboard (I picked one up at www.audiomidi.com for around $100 and it came with a version of Live Lite.)

I also recently had a M-Audio Fast-track given to me and it's got Live Lite (I think version 5) in the box on CD.

Here's Live 7 LE for $150 at audiomidi.com http://www.audiomidi.com/Live-7-LE-P10991.aspx

Or go for the controller from Akai that was recently announced and has Live 8 (a cut down version of some kind) that's designed for triggering Live sequences. It's 400$ and there's a comment about a patch for a free full version of Live. http://www.audiomidi.com/APC40-Ableton-Live-Controller-P11924.aspx