Compact external switchmode powersupply?

[AmmoJammo]

I'm looking for something to run my A600 that doesn't take up as much space as the A500 brick I have, or weigh 1.8kgs like it does...

I'm struggling to find a good quality +12 and +5volt powersupply.

I've been looking at external hard drive power supplies, such as this:
http://www.ebay.com.au/itm/12V-5V-AC-Adapter-For-HARD-DISK-Drive-Power-Supply-IDE-C99D-/360547355503?pt=AU_Components&hash=item53f24c0b6f

But obviously the quality is extremely low!

Acquiring the -12v from a supply like that shouldn't be too difficult, and I only need ~35watts total... but none seem to have the current on the +5v rail that I'd like either...

I've pulled apart two laptop supplies, thinking I may be able to modify them for +12v, and add a switchmode +5v regulator internally too, but there's no space in either of them....

So... ideas?

I saw the Xbox 360 supplies, that do 12amps at 12volts, and considered adding a 5v regulator, but this seems a bit overkill...

Thanks!

[AmmoJammo]

you really want at least 4.5 amps on the 5v side. this would be tough to do with a linear regulator(and would likely run really hot).

Hence the suggestion of a switchmode regulator Something like the Maxim MAX787, does 5volts at 5amps with a fairly small number of external components.

Of course, finding a power supply that does 12v at 2amp and 5v at 5amp to begin with would be a lot easier!

I'm now considering two separate switchmode power supplies, built into a smallish jiffy box

[AmmoJammo]

You can't use a linear negative voltage regulator, unless you have a negative voltage to begin with.

The power supplies have a diode (or pair of diodes) on the transformers output winding, you can simply add another two diodes, reverse polarity, on the +12v winding to get the -12v

Realistically, a 12 volt, 6 amp power supply (72 watt) should be able to do 5volt at 10amps with a switchmode regulator, after accounting for losses.

So 6 amps at 12v should be good for 5v @ 8amp, 12v @ 2amp

The PSU's I have now (three of them!) are heavy linear supplies, rated at 5v @ 4.3a, 12v @ 1a.