well instead of a reservoir you could do a T-line
the part with the bubbles in it, is the T-line....that pic was taken right after I had re-set up the water cooling for this particular motherboard so the system was still bleeding itself (getting rid of the bubbles)
T-line will save you some space.
As for water, you'll just need distilled water and 5-10% of anti-freeze or zerex, which is basically anti-freeze but it's supposed to be the best out there for make sure your water stays clean.
There are heatercores out there, but there are different ones.
That right there is a heatercore and it's very similar to the one I got, but in reality there is a difference. It's a 1977 bonneville heatercore like mine, but this one is model number...ehh actually I forget...mine is 2-302 which I said in an earlier post...it's a bit thicker than the one you see in that picture there which is basically the only difference..
Also of course you'd want to try and get the copper heatercore for better transfer.
The only place I know of that sells modded 2-302 heatercores is a dude named 'weapon' over at xtremesystems....he even makes a custom CNC machines shroud and puts in 5/8" barbs in his heatercore...I also modded mine with 5/8" barbs, slightly bigger than 1/2" which is generally the standard.
But if you don't feel like modding and you can find a decent heatercore for a good price then go for it.
Heatercores generally outperform radiators quite easily.
Radiators you have one pipe that just goes back and forth which is surrounded by (generally aluminum) fins for heat transfer and of course the fans blowing on it cool it down.
With a heatercore...it actually goes through really thin fins, instead of a winding pipe....this effectively cools the water more efficiently because the water is thinned out so more of the water can get the benefits of the fans cooling it...with the single pipe winding around, it's like tube steak in a microwave (except we're talking about cooling but the principle exists) the outside would be cooled first and the insides might not get cooled at all....with it going through the tiny flat fins of a heatercore each bit of the water is more likely to be cooled.
now what this translates into in terms of actual cooling difference....well you'd have to do some tests with a radiator, then a heatercore in a computer and find out for yourself. Basically I'm saying I couldn't give you an exact number