Thanks again everyone for the info.
I wasn't really trying to get the servo to push my hand out the way, just simulate a high enough load to see how much current 1 servo will attempt to draw. That way I could just estimate the maximum current the 6 servos may attempt to draw on very high loads.
I was trying to avoid having 2 power sources (i.e. a 9v battery for the atmega328 and 4x AA batteries for the servos), but if this is the ONLY way to do this I may have to bite the bullet on this and do just that, or possibly go for a wall wart to replace the batteries all together. A wall wart does slightly worry me just because I'll be dealling with the mains electricity, but if that gets me what I need instead of having a large number of batteries in this, I may have to consider this route.
If I had a 5v 2.25A wall wart, I take it this would be fine to power everything (in this situation I guess I wouldn't need any regulators/capacitors either as the wall wart is converting everything to 5v regulated DC for me)?
Here's a link to one (but it seems pretty pricey to me, so I'll see if I can find one on eBay or any electronics around the house that I don't use anymore) http://www.maplin.co.uk/ac-dc-fixed-voltage-switched-mode-power-supplies-48484
I'll definitely take a look into some rechargeable NiMH batteries for this, as it will save costs in the long run if they're rechargeable.
Thanks for pointing out datasheets for batteries. It's good to see that they can produce 2A of current, as short lived as it may be (30 mins I think before the voltage starts really dropping according to the energizer AA NiMH sheet).
I figured the power side of things would be the easy part getting into electronics, apparantly not!