S2865 or S3870

Hola,

Another question:

For an office application currently running slowly on a dual PIII-1.13GHz
system, would you go with

S2865 and Socket 939 dual-core Opteron 170 (2.0GHz) + 4GB PC3200

or

S3870 and dual Socket 940 single-core Opteron 246 (2.0GHz) + 4GB PC3200

?

I'm also looking at power draw, which would be about 80-90W less with the
single dual-core.

Thanks!