What hardware are you trying to image? Some vendors (eg Lenovo) have their own recovery systems which use a boot manager that can be difficult to clone. I found for example that Norton Ghost 15 cannot handle the Lenovo boot manager so this one would be a waste of your time if you have a Lenovo machine.
If your hard disk is on the way out, I would recommend backing up all your data, as the rest can always be reinstalled but data once lost is gone forever.
You can use GSS 2.5 to create WinPE bootable media so that you can boot your system from a CD or USB device and then image the hard disk using Ghost tools.
For advice on Symantec BESR, there is a separate forum on Connect where you will find some very experienced people to advise you further. However, I believe BESR performs "hot imaging" with the host operating system running on your target machine, and personally, I prefer to have my target hard disk offline when imaging it.