Upgrading from a T5600 to a T7200 would be a reasonable upgrade
Upgrading from a T5600 to a T7600 would not be advisable
T7200 = Memron 2.0GHz 4mB shared L2 Cache = $300 (the average retail price right now)
T7600 = Memron 2.33Ghz 4mB shared L2 Cache = $650 ("")
So, you'd be paying $350 for an extra .33Ghz, everything else including the chip revision is identical
All companies do this, they sell their 'flagship' hardware for a ludicrously higher price then the model just below it to cater to the market of rich people who insist on having the absolute best ... even if it costs substantially more. Maybe it has something to do with penis envy ... or maybe rich people just don't have common sense ... cuz if your rich, hell you can buy common sense :P
So if your rich, go nuts with the T7600, and while your at it send me some money cuz im poor :P
However, if you can contemplate logic and/or common sense, stick with the T7200