You would have been better off over in the Microsoft forum but I'll give it a shot.
What happened to the original harddrive in the 6730? Did you overwrite it with the info from your old machine or physically swap out the drives or add the old drive as a secondary drive?
If you did either of the first two then it's not going to work. If the third then you still have a chance. You probably just forgot to set the jumpers to make your new drive the primary and the old drive the slave. Go into CMOS (BIOS) setup (hit F1 when you see the HP logo) and see if it detects both drives. If not try F5 to reset the defaults then F10 to exit and save.
http://h20015.www2.hp.com/en/document.jhtml?reg=&cc=&lc=en&prodId=hppavilion20888&docName=bph07110&cat=setup#P45_3217IF that doesn't help then it's the jumpers - do not blindly set the jumpers to Master and Slave. Some PCs use Cable Select where the connector on the cable determines which is the Master and which is the Slave. Usually the cable is clearly marked with Master and Slave. Fix them and it should work. See:
http://h20015.www2.hp.com/en/manualCategory.jhtml;jsessionid=JPFYSUE1VVAS3QEXGR5UOSQ?reg=&cc=&pagetype=manual&prodId=hppavilion20888&lc=en&sw_lang=en&docparent=manual&cat=manualwhich should all be one long line.
If one or two then remove both cables from the drive and start it up with a boot floppy. (You may need to change the boot order in the BIOS or set a dipswitch on the inside in order to do this.) This should work and should verify that you haven't killed something else.
Turn it off and hook up the power to the drive but leave off the data cable. Try to start it up again with the boot floppy. Some drives can die so hard they suck all of the power from the Power Supply.
Finally hook up the data cable making sure that you have it on correctly at both ends. The red line indicating pin 1 is always on the side nearest the power supply connection. Verify that the redline is next to pin 1 on the motherboard.
Go into the BIOS and see if it sees your drive. IF it does then you still be to boot from a floppy or CD. See:
http://h20015.www2.hp.com/en/document.jhtml?reg=&lc=en&cc=&prodId=hppavilion20888&docName=bph07119&cat=setupThis will kill off all of your data so you might want to get a new harddrive and set it up then put the old one as a slave and copy the data only.
Ron