With the 37mm you don't need many rounds to bring down anything but for one you don't have many and for two it's a very slow rate of fire. I prefer anytime 2 x 20mm... The 37mm is also nice x 2 on the JU87 G type (Stuka) for tank busting.
On the Pacific front the Cobra has a hard time. The P400 version above has only a 20mm in the prop.
I run at 1440 x 900 with AA x4 AF x8 Intel Core Duo E8500 and ATI HD 5850 graphic, not a monster, built it more than 2 years ago and changed the graph card from 4850 to 5850 last Xmas. Running with XP pro which needs less ressources. My IL2 also runs with a compilation of mods made by the french website Check Six and I have been collecting skins since the very beginning. I use IL2 Mat Manager 2.36 for better decals, IL2Stab for launching and tuning and IL2Dcg to build dynamic campaigns.
My IL2 install is now around 21 Gigs...
Best thing I bought is a Track IR... I couldn't fly without anymore...