Figure $150k+ per car per race to have the full car, aka not worthwhile.

A much better option would be running commercials, say on Adult Swim, or on something like G4 TV.  Each spot could be done for a few K depending on the time it runs and some other factors if you wanted to hit mainstream.

Billboards can be done for ~$1.5k per month depending on the area too.

Thanks!  As for overclocking, any idea on how much that would bump it up from the 800 W level?

CPU: AMD Sempron 140
CASE: open (n/a)
HDD: 16 GB SSD
3x ATI 6970's (slight overclock)

Do you think I can reliably run 3 of these ATI's on a 1,000 Watt PSU?

Using Newegg's Power Supply Calculator, it says I would need 1168 Watts.  Hoping to get by with less, if possible.

That's a myopenpc case right?  How is your bottom card mounted?  I notice it's sitting higher than the top card.

I enjoy Ruby/Perl/Linux (coding) and would love to contribute to some interesting bitcoin related projects.

So you're doing about 1 Megahash per second, which is very, very low.  It would take a long time to generate a block at your current rate.  I would suggest that you join a bitcoin pool, or build a mining rig, or both.

CPU : Doesn't matter, get the cheapest CPU possible for your motherboard.  The AMD Sempron 140 is recommended a lot.  A lot of people downclock their CPU to conserve power.
RAM : 1 GB is enough for Linux, for Windows 2 GB is the way to go.  Get the least amount of sticks as possible.
HDD : Go cheap and small here.  If you can get a cheap 30 GB SDD, do it since it's more power efficient.
OS : I prefer Ubuntu if you wanted to go Linux as a lot of tutorials and drivers are geared for this Linux distro.

I'll let someone more experienced address the PSU/motherboard options.

I'd like to contribute to the frontend pushpool code (I know Ruby/Perl and some PHP), there's a thread here http://forum.bitcoin.org/index.php?topic=8760.120 that I'd like to reply to.

Thanks in advance!