I need to download the 64bit version of Ubuntu 10.04, I found this link http://releases.ubuntu.com/lucid/ and select this option:
PC (Intel x86) desktop CD
But it is x86? And the other 64bit option just for AMD processor
It's not just for AMD, it works for my Intel i5 processor as well, that was merely a naming convenience.
Also, consider the 12.04 version instead, as 10.04 is going to be obsolete.
Today's processors are almost uniformly 64 bit. Intel copied the 64 bit architecture from AMD when their own 64 bit Itanic tanked. (Even my Intel Atom netbook is 64 bit). The one you should use is the AMD64 one, the x86 is 32 bits.