Min 4 drive NAS media server, old computers, Please HELP

(RAID Newbie) Trying to make a media serving NAS like this http://www.tomshardware.com/forum/ [...] erver-htpc

without buying expensive raid controller, and using an old computer. I have a few old dual core computers from work that i can use.
Currently I have my quad core computer with 2 1tb hard drives attached that are full of media, and another full 1tb that i plug in with more movies etc on it.

I want to set up something similar to that guys raid 5 with hot swap drive. I plan on buying more hd's soon even with the tsunami, I need help on what to get or if i should just not use old computer and try to make a cheap option some other way. I was looking at cards like
will this work and also need help with breakout concept can i just have 2 internal ports and breakout to more drives.
do i need to buy new power supply etc to power this current old computers which are all around 300W even in my computer

Or should i just be lazy and use something like this

1) Raid controller suggestion
2) Power supply suggestion if need be
3) can I use older computer, or mine, or do i need to start from scratch

I need to remedy this situation soon any help would be appreciated. Thank You