If you are able to boot the machine up then go Start - type msconfig and press enter.
Click on the Boot tab and check the box for Safe boot and then the one for Network - Apply - OK - Restart.
This will give you Safe Mode with Networking.
This will permanently boot you into that mode so to revert to normal mode, go back into msconfig/Boot and uncheck the box for Network and then the one for Safe boot - Apply - OK - Restart.
If you want to go to the Recovery Environment or the machine won't boot, then you will need to boot up with either a System Repair disk or an install disk that includes SP1.
If using an install disk, then click on Repair your computer on the Install screen.
Generally though if F6 or F8 are the keys you would tap for your make and model of computer do not get you into the advanced boot options, then you would normally factory reset an OEM machine or do a clean install on a purpose built machine.