CNC Spindle power and rpm HELP!

Hello!

I am making my own cnc machine. The working area is 1m x 1m.
I will mill wood and probably aluminium.
I will cut some thin wood and want to mill in the wood some precisious work also.

I am about to buy 2.2kW water cooled chinese spindle driven by VFD.

Can you reccommend me what is the best for me - there are THREE factors to discuss:
- cooling type
- rpms
- power.

Under that are linked two spindles, one is 2.2kW watter cooled 24000 rpm,
one is 3kW air cooled 18000 rpm
and one is 3kW water cooled 24000 rpm.

What about that AirCooled 3kW spindle what do u think? it is different.

Here are some links:
- http://www.ebay.de/itm/CNC-2-2KW-Sp...SwX6VTyI2u&clk_rvr_id=919825955223&rmvSB=true
- http://www.ebay.de/itm/3KW-WASSERGE...Swl9BWLZXP&clk_rvr_id=919824856592&rmvSB=true
-http://www.ebay.de/itm/3KW-LUFTGEKU...SwKrhVVYTt&clk_rvr_id=919818177266&rmvSB=true


THANK YOU