If your Uno has the 28 pin 328 chip, there is an extremely easy way to copy the Uno bootloader and fuses to a new chip. I have done it many times, takes a couple minutes.
Download eXtreme Burner Avr (it's free), plug your USBisp onto the ICSP header of the Uno, select Atmega 328P from Chips menu on Extreme, do a Read All, replace the 328 on your Uno with the new 328, do a Write all.
That's all there is to it. Easy as falling off a barstool.
If you don't have 328P on Chips menu (my older version did not) come back here and let me know. I will post the fix. You only need to add an item to the chips.xml file and replace the Fuselayout.xml file. You can do it with Notepad.
With eXtreme GUI software, you can also load and flash any .obj file to a chip and modify the fuses any way you want. Use Engbedded.com to calculate fuse values. I have also used it many times for flashing bootloaders onto ATMega8 chips. eXtreme GUI software is free but they beg for contributions. I was so happy to find this app after pulling my hair out for hours, I shelled out a few bucks for them.
This software worked fine on my Win7 computer, but if I remember correctly, I had to get LIBUSB0.DLL before I could run eXtreme on my Win8 laptop. For some reason, it is not included in Win8 and is needed for some USB stuff.