Better get a PSU with a fan on the back. Those other PSU's do look more sexy but really those traditional PSU (with fan on back) are really silent as wel and no extra heat build up in your case..
To give 1 example: http://www.anandtech.com/casecoolingpsus/showdoc.aspx?i=3306
Bit pricey though.
I got an Antec NeoHE Power 500w and it's really silent. (â‚¬80)