Is This Supposed MacBook Pro Update Coming Soon, Worth It?

Hello, I have an early 2008 MacBook Pro. It’s getting on in years and starting to run slowly and have minor issues (such as turning off the second it’s unplugged from the AC power source). I’ve been hearing rumors about a minor update to the MacBook Pro line with the change being just a faster Sandy Bridge chip in it. But awhile back I’d also heard about potentially more dramatic updates in 2012, such as a redesign for the body and such. My question is this. Do I keep putting money into fixing this computer and wait until a future update? Or will this minor update coming soon be as good as I’m going to get for awhile and probably worth just upgrading now?
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David