Vista Dimension 9200

Rebuild my 9200 Dell dimension with the power supply, two new hard drives and a video card. Was able to upload all the drivers and put the computer up to date. Everything seems to be working except when I power up the machine I get a F1/F12 option. The computer won't directly boot from the hard drive as it should. What could be possible problems? How can I correct this so that I don't have to press F1 to continue or at 12 to get into the bios?  I have set it up in the BIOS, driver settings so that the hard drive is the first and only drive ti should boot from.  

Using Windows Vista OS.

any help is appreciated.