Hmm.. Ok, I added a bit of info to my initial post; you may need to reload to see it.
I have used InfraRecorder in the past, a few years back was the last time I used Windows
so it may be updated since that time. However, it was a great, easy to use tool.
I remember it being a two-click process to use it to make a Linux CD:
1) Click the menu button for "Burn ISO image to disc"
2) The file-locator window appears, where you point the tool at the .ISO file you have. Select the ISO, and click OK.
3) Press GO!
That should burn the disc. If you have the option, Select a very slow burn speed, like 2x or 4x, as this will help guarantee a good burn.
Now, the location where you downloaded the ISO image FROM, should have a file called "md5sums" or "checksums" or "sha1sums", or these checksum values will be displayed right there on the download screen, where you got the Ubuntu image (or Mandriva or whatever).
For Windows, Google for "md5summer" and get that tool and install it on Windows. Then, BEFORE BURNING THE DISC, use "md5summer" to verify that the ISO you downloaded has the same checksum value as that which is shown online on the download page, or in the checksums file or "md5sums" file.
If it matches, that's good. Your download was OK. Now burn the Image to Disc.
After the burn, it's recommended to verify that the disc burned correctly. On windows, I'm not sure how to do this. I've never used md5summer myself either, so another member will have to advise you how to verify the burned CD.