Funny how budgets can change is the a57 that much better than the a37?
Depends what is important to you - I actually prefer the smaller size of the A37 but I can see why others may prefer the bigger A57 ergonomically.
The differences between the A37 and A57 are:
* Size and weight: (A57 is quite a bit bigger and a little heavier)
Sony SLT-A37 dimensions: 124.4x92x84.7 mm (camera body only, excluding lens) weight: 506 g
Sony SLT-A57 dimensions: 132.1x97.5x80.7 mm (camera body only, excluding lens) weight: 618g. See:
http://www.dpreview.com/previews/SonySLTA57/images/sidebyside1.jpg
A57 body being bigger and heavier obviously can be an advantage (ergonomically for some, balance with heavier lenses) or a disadvantage (more bulk and slightly more weight to carry around). The A57 seems like better build quality/more solid but that might just be the extra size and weight?
Compare dimensions and weight here:
http://camerasize.com/compare/#326,313
* Larger lcd screen on A57 - 3inch vs 2.7inch on A37
* Much higher resolution lcd screen on A57 - 921600 vs 230400
* Higher maximum FPS (frames per second) on A57 - 12 vs 7 on A37
* Horizon level in A57 but not A37 (Virtual Horizon feature)
* IR remote in A57 but not A37 (both will take a corded remote: ie: Sony RM-L1AM or a much cheaper generic equivalent - try ebay/amazon)
* Longer battery life on A57 (bigger battery)
* Swivel screen on A57 vs tilting screen on A37 (Swivel screen can also fold inwards with the lcd against the body to protect the screen)
* Different button layout: 'Zoom' button on A37 does not work when shooting raw and cannot be programmed to anything else - ISO or exposure compensation for example would be very useful - Sony, please fix this in a firmware update!) On the A57 there are two dedicated buttons for ISO and Exposure compensation right next to the shutter button for easy access - the A37 only has the 'zoom' button on the top plate and it's just a useless gimmick and misleadingly named (only works for the extended zoom feature which is pointless: just crop in post)
* Video: A37 has 60i and 24p
* Buffer: Much larger buffer on A57: (Full specs are: A37: 18 JPEG, 6 RAW vs A57: 25 JPEG, 21 RAW)
That's about all I think?
Otherwise they are essentially the same camera in different sized bodies (same sensor and processor). While I like the smaller Alpha bodies like the A55 (discontinued) and A37 (current) the larger higher res full swivel screen of the A57 is MUCH nicer than the screen on the A37. I like the way you can also turn the A57 screen inwards to protect it and also prevent constant smudging from your nose. But I can live with the A37 screen given the cost savings over the A57 and that I mostly use the evf anyway.
For me the biggest differences are the size obviously, the lcd screen and the two top buttons for exp comp and iso on the A57. However also being on a limited budget I didn't think the price difference of the A57 at over £400 vs the A37 at £240 was worth it - I didn't need the kit lens and for the price of the A57 + kit lens I could get the A37 and 2 prime lenses (35 1.8 and 50mm 1.8) which suited me better. But I might get an A57 if I can find a bargain when it's replaced by a newer model.
If you are not planning an upgrade for a long time then the A57 might make more sense though?