-> Is this true?  I have a P2-266 machine with 128MB running 98SE.  I
-> either have a spare 64MB chip, or a 32MB chip (depending on how I
-> configure another system).  Would the machine benefit at all by
-> being bumped up another 32MB or 64MB?

Win98SE will be Helped by bumping the Memory up to 256.  Beyond that for
the typical user the advatage is not worth the cost. 

  
-> For that matter, will 98SE run fine on a P-200MMX with only 64MB RAM?

Depends on your Definition of Fine. I have seen satisfactory, but slow
operation of Win98SE on a 486/66 machine. 
But for light duty applications, no heavy picture editing or large
Databasse/Spreadsheet calcualtions, a 200 is just fine for Win98SE.
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