Start up Problem

If you have any USB devices plugged in, remove them and restart.

If that doesn't work,
1. Boot from the Windows 7 install disk
2. After choosing your language, choose the "Repair your computer" option on the "install now" screen
3. Optional step: if you need special drivers to access your hard drives (SCSI, etc), follow the "load drivers" onscreen instructions to read them from an external source.
4. When prompted, choose the "System restore" option
5. Choose one of the previous restore points (I chose the second one down on mine just to be sure)
6. The system will roll back installs to that restore point; reboot only when prompted
 
If your pointer is visible, then it's past the POST, but sounds like something is wrong with your OS (maybe with the hard drive, also/instead). I think ratedk pretty much has you covered on troubleshooting here though.

Only other thing I would recommend to supplement is to get to a command prompt via the recovery options listed above, and type: bootrec.exe/FixMbr

If that command is a no go, try: bootrec.exe/FixBoot