Ouch.
My T61 laptop has been throwing Trap 7Fs or C000021a Fatal System Error occasionally overnight, or losing its WiFi connection overnight, or just acting weird for no reason. And even when it's running, it seems to often be a turtle these days. :-(
AppleInsider has a report that MB and MBPs are going to finally be updated in the next few weeks. http://www.appleinsi...ok_line_soon.html
You might want to wait, if you can. Their desktops are getting long-in-tooth, too.
Good luck.
Cheers,
Scott.