Question : Problem: what went wrong with this pc build

Hi EE, I have built allot of computers & this is a new one for me. I had an Intel Badaxe d975xbx2 mobo, 4gigs kingston kvr667d2n5/1g ram, intel x6800 extreme, geforce 7952x2 video, thermaltake 850 w power supply,2 sata drives, dvd, cdrw, sb audigy zs, etc. This computer was working fine. I also had an asus p5n32-sli se deluxe mobo, & 2 geforce 8800gt. All i wanted to do was swap the mobo & put in the 2 8800's. It would not post. I tried clearing the bios as it said in the manual, not.I tried different approved memory that was working from another pc. not. I went to put back the original computer & it keeps freezing during vista install or sometime it won't even post. The fans are working fine and the cpu heatsink feels cool. How do I get the original pc working. Very strange.
                                      any help would be appreciated       thanks  Ed

Answer : Problem: what went wrong with this pc build

some notes :
1- you cannot just swap different boards for XP; it is NOT recommended, and needs at least a repair install; read more here :
http://www.michaelstevenstech.com/moving_xp.html                  Moving XP
http://support.microsoft.com/kb/249694                                "         "  
2- if it does not post after the change, i suggest you chack everything you moved, and connected; it can be a mounting post shorting the mobo,  bad ram, bad inserted, wrongly oriented disk / cd drive connectors, or even the front pane connectors
i suggest you test mith a minimum setup : (if possible out of the case, on anonsulating surface like hardboard)
mobo + cp u + 1 ram stick, video card, PS --> any post? then connect devices till the bad one is found
3- you may have caused static discharges while swapping parts, so test at least ram and disk; you can find both on the ubcd :  http://www.majorgeeks.com/Ultimate_Boot_CD_Full_d4981.html
you do this on a working PC !