Linux
=====
It is highly suggested to MD5SUM your ISO before burning a coaster to do this in Linux / Ultimate Edition it is simple supposing in this example you have downloaded it to your desktop using UE 2.6 32 bit ISO open a terminal Applications >> Accessories >> Terminal and enter the following:

cd Desktop
md5sum ultimate-edition-2.6-x86.iso

it should return the following:
cf9e2d59c8921c49f0d7b9e8972061dd  ultimate-edition-2.6-x86.iso

If the hexdecimal number is anything different you have a corrupt download and should download it again, sorry.  See below chart for other O/S's.

Once you have verified your ISO is good... Burning an ISO in linux open K3b Applications >> Sound & Video >> K3b:

Select more actions at the bottom select burn image and select the ISO you just downloaded.  IMPORTANT!!!  Select the slowest burn speed your drive is capable of burning, this ensures you burn a good copy.

Windows:

Grab a MD5sum tool for windows:
http://www.md5summer.org/

Browse to the folder you downloaded the ISO and hit Verify sums once again please see chart below.

Burning:
Use your favorite burning tool be sure to select burn image and burn at your drives slowest speed.

Enjoy Ultimate Edition,

TheeMahn
MD5SUM                            Release
=====================================================================
b62c2177f7f34c35a5641ff884768684  ubuntu-christmas-2006-x86.iso
aa4af59aecb14a860f5d2f03f3dec807  ubuntu-ultimate-1.2-x86.iso
44a05b7453b041130d57a828613759cf  ubuntu-ultimate-1.3-x86.iso
c95a3f7121c1f2888f7e6689f1286ea0  ubuntu-ultimate-1.4-cd.iso
ba37bdad19922f4ecda5a9f15faa7af7  ubuntu-ultimate-1.5-x86.iso
873b8f077d268d376854ee38923ad602  ubuntu-ultimate-1.6-x86.iso
41733d8e7458e0c8ae113b556922c35d  ultimate-edition-1.6-gamers-x86.iso
e1ffdcc7d736aeaefda48943513133e6  ultimate-edition-1.7-gnome-x86.iso
af01c20a495c07bc43264ca95b5735e0  ultimate-edition-1.7-kde-x86.iso
34ddf6a96cc88615d283668eaaeebc20  ultimate-edition-1.7-x64.iso
1abddea24a762728efe1e55e74df1d67  ultimate-edition-1.8-x64.iso
61f124ffec0490af67aaa81734ab4524  ultimate-edition-1.8-x86.iso
01fee6d3fca8e2ace89bfef7b85e9d35  ultimate-edition-1.9-x64.iso
c08bc6663406d0c771384938f128ec31  ultimate-edition-1.9-x86.iso
375b33937ab2070ddaee486f77c5fbfc  ultimate-edition-2.0-gamers.iso
8e44825cf347cec8f30786befc1be3c4  ultimate-edition-2.0-x64.iso
7fa893d61bc2b4c5f982c98f679fddfa  ultimate-edition-2.0-x86.iso
aa58536d986c156b418a2faf8a4f6411  ultimate-edition-2.1-x64.iso
4d957b58509af62b784628ee8d6d4f46  ultimate-edition-2.1-x86.iso
e244433f33dd9040e811aa52cde70472  ultimate-edition-2.2-x64.iso
70317956170f77d5f366bdcce594a9e5  ultimate-edition-2.2-x86.iso
dfed949027ff6c1702f3736e8ad2f2b6  ultimate-edition-2.3-gamers-x86.iso
de7b5156fd7ec104158e6e401fb88246  ultimate-edition-2.3-x64.iso
2ec4d3a0012aa0c999eb0eedc1e24f1e  ultimate-edition-2.3-x86.iso
d605b7ee4968977f1d9086bffdc2d5be  ultimate-edition-2.4-alpha-x64.iso
8732760a7d021879c26a9a8d73cc79da  ultimate-edition-2.4-x64.iso
f666c59377e69b541743a4fb4f35aa52  ultimate-edition-2.4-x86.iso
cf13b6229a2094658c64cf815bc606ff  ultimate-edition-2.5-x86.iso
72699b8b11c7ebe8ce6e7e5071269079  ultimate-edition-2.5-x64.iso
f048342826bcc7bf9986f36b18b48e0b  ultimate-edition-2.4-gamers-x64.iso
31d61c4f93cc1121690bd289a68e37e5  ultimate-edition-2.4-gamers-x86.iso
7d3cd6f46af7c66ed7e4df1657bc5ea5  ultimate-edition-2.6-x64.iso
cf9e2d59c8921c49f0d7b9e8972061dd  ultimate-edition-2.6-x86.iso
26c4ff8e0249e662f5dc86bc16d937e4  ultimate-edition-2.6-gamers-x86.iso
9a382b7c8c112e1894634fbbb4582fec  ultimate-edition-2.6-gamers-x64.iso
0b82382322790c27a43f3d8815f09001  ultimate-edition-2.7-x86.iso
fd5f2b0724ebb2507625383e702e7b90  ultimate-edition-2.7-x64.iso