My ps2 keyboard is broken. So i buy new usb keyboard and it works good.
I am wanting to install a fresh OS (Windows XP Prof.), but when i start it up (with the OS CD in the CD drive)- the keyboard lights up (like it's working) but when it comes time to Press any key to boot from CD...the keyboard doesn't work. (It goes to bios and works fine with configurind boot option)

Try inserting the keyboard in a different USB port or look for USB options in the BIOS. Then again try checking the keyboard manual or go online. You can even bug the Keyboard company's tech support.

There are times when I'm servicing a PC and there is no PS/2 ports so I have a spare USB keyboard and mouse. Sometimes it takes a couple try(s) in different ports to get it. Other than that it is just timing. Maybe your CD is bad. What you could do is use another boot CD that formats and copies the files to the PC. Then run the installation from the command line. Ha ha, that's just an idea.

With my bluetooth wireless keyboard (Microsoft Wireless Entertainment Keyboard 8000), I find that the keyboard works during the booting of the computer (so I can navigate through the BIOS settings and configuration) but it doesn't respond during the loading of the OS, which in this case is Microsoft Windows Vista Ultimate. This, I believe, is caused by USB being disconnected on startup of Windows so that Windows can load the USB keyboard and mouse drivers. Once a screen came up asking me whether I wished to boot into safe mode since my computer did not shutdown properly, I couldn't use the wireless USB keyboard to access any of the options.

I think it is handy to keep a keyboard and mouse which uses the tradition serial ports for those devices.