The Finns in their struggles witht the Soviets found a good use for the lowly Brewster Buffalo. The Buffalo was much despised by those who flew it in combat for the US, Britian, Australia and New Zealand but to the Finns it was a gift froom the gods. I suspect that the reason for the succes of the Buffalo in the service of the Finns was due to the "relatively" poor quality of the Soviet air arm at this time.
If I am not nmistaken the chief opposiion for the Finns would have been the I-15 and I-16 fighters, aircraft that would have had a performance roughly equal to the Buffalo. Given aircraft of equal ability the tide will turn to the better trained piolts. Also the Finns would have had the advantage of fighing over thier own country for the most part, refer to the Battle of Britian for this advantage.
Any excuse for a few pictures, EH :-)
A pic of a Brewster Buffalo in Finnish Service,a hat tip to www.warbirdalley.com for the pic
And the Buffaloe's oppostion, hat tip to www.warbirdsovernewzealand.com for the Soviet pics
A pic of the I-153 Biplane, IIRC the I-153 was the version of the I-15 that had retractable landing gear. 
And a pic of the I-16 Rata
Well off to work the insulboard and sheetrock are calling me :-)
Regards
alfa6 ;>}