If anyone can help with this that would be awesome.  
 
Just to clarify my guess is my power supply isn't up to par for what I need it to do however it doesn't explain why single card won't load anymore.
 
I'm runnign Windows Vista 64 bit, with Asus P5K-E Mobo, 4gb ram 465W psu
 
My original card is Ati Asus 3850. (everything is fine)
 
Received a ATI Sapphire 3870 today and installed in primary PCI-E slot, and started computer (without 3850). Got driver errors was asked to reboot, did so and now computer will not boot, simply says Boot error reboot and select primary boot drive or install boot disc. If i put in my vista DVD and try to repair, it can't find the restore files. I tried to replace the new card with the original card and still no luck. Same problem. I would like to not have to reinstall vista and loose what i've setup at this point so any help would be great. Thanks
 
Conclusion:
 
Either PSU is just way too underpowered (not explains why single card doesn't work) conflict btwn Sapphire 3870 and Asus 3850.

Sounds like corrupted windows or the PSU hiccuped and damaged your motherboard or hard drive, that's my guess.

Anyway to repair it if its just a corrupted windows?

So basically right now as I can understand it. My computer can't detect my Hard drive, i've tried unplugging it and plugging it back in. Any suggestions. I figured this when i attempted to reinstall Vista and the HDD isn't showing up and no drivers detected pops up.

this is gonna make me sound stupid but i figured out the problem..... I forgot to plug the Hard drive back in...

 
 
Hahahahah not stupid at all funny but not stupid.  
 
I just recently upgraded my system and I plugged everything in and went to boot up and got nothing but beep codes.... I forgot to plug the power cable from the video card into the power supply lol

lol, now i just have to figure out if my PSU will handle these two graphics cards.

I could not tell you, I do know that if it does work with your PS, I would keep an eye on your system temps. I don't know if power supplies get hotter if you use more capacity.  
 
I had an older power supply a long time ago (when 300 watts was plenty lol) and I upgraded to a monster system and I swear the paint almost melted off my case so I had to replace it with something better.
 
Edit: Although you probably wont damage anything in trying and best of luck to you !!!  
 
hmmm another thought you may wish to google for some sort of power calculator, I dimly remember something about being able to put your system specs into this web site and it would tell you how much of a PS you needed. (probably on Antec's web page or another one of the PS companies)

Well I found this but they want $1.99 for the "pro" version which has information about SLI and that sort of stuff.
 
http://extreme.outervision.com/psucalculator.jsp
 
Edit: The free version does have SLI so you might look into that (its just a web page) and with my system specs it says I could make it with 390 watts at 90% load.   I have HE 550 watt so im good for now lol