Solved! Processor chip replacement

Solution
Those Vaio's use PGA chips, so are theoretically replaceable - whether a given cooling solution is good enough for anything stronger though, is unknown.

There's not likely to be a compatible i7 for that laptop though.
If your NS is from ~2007, the first desktop class i7 didn't launch until mid-late 2008, with the first mobile i7 in mid-late 2009.
Those Vaio's use PGA chips, so are theoretically replaceable - whether a given cooling solution is good enough for anything stronger though, is unknown.

There's not likely to be a compatible i7 for that laptop though.
If your NS is from ~2007, the first desktop class i7 didn't launch until mid-late 2008, with the first mobile i7 in mid-late 2009.
 
Solution