Transformer question (only slightly OT)

[Chuck Guzis]

I have a power transformer that I scavenged out of a 15-year old UPS, so
it's probably pretty close to being on-topic.

At any rate, I want to use this transformer in a DC power supply.  I have
three sets of windings:  two sets are 120/240v "universal" series/parallel
type and the third is 24-0-24v center-tapped.

I want to run this from 120vac.  

Is there any benefit to paralleling the two sets of 120/240v main windings
(i.e. 4 120v windings in parallel)?  Will it increase the power rating of
the unit or is that mostly a function of the secondary winding?

Suppose instead of 24-0-24 on the secondary, I'd like 12-0-12.  Obviously,
one way to get this is to hook the primary (-ies) up as 240v.  Is there any
benefit to be gained in parallelling the two 240v primaries?

Thanks,
Chuck