Nah BT is still pretty close on.
64 Bit is important due to various reasons, the majority of the speed boost comes from something not directly related, though 64 Bit does come in handy for DSP based algorithims is my understanding, which not surprisingly is most of what he listed.
Also 64 Bit works great if set up properly, like most things in linux. I cant speak for Ubuntu or any other packaged distro of that nature as I havent ever used them 64 Bit, however running 64 Bit on my Linux(Gentoo) box has been something I have done for quite some time. There are some programs that wont compile as 64 Bit due to them not being written for compatibility with it, or a few other problems that show up, but overall it is a very strong experience... espsecially these days.
In as far as Flash is concerned, you need to install the 32 Bit version of Firefox in order to use it, but it works fine. This happens in a variety of things, the primary reason is because of IPC between 32 Bit processes(Flash) and 64 Bit processes preventing it I believe. At any rate how it translates for audio is a 32 Bit precompiled plugin cannot be loaded into a 64 Bit host. This is true for any program is my understanding. Mainly only becomes an issue with VST, which is the only thing that might make me use the 32 Bit compiled version of Ardour instead of my currently running 64 Bit.
So all in all, if it doesnt run the 64 Bit correctly, run the 32 Bit and you will be fine, and just as well off if not better than running a 32 Bit distro.
That being said, noone has yet addressed the original problem mentioned, which seems to be a faulty xorg.conf file setup, unless he is getting a graphical login screen and then it stops working after logging in. The first step would be to start there and see what the problem might be, my first thought would be incorrectly set refresh rates on the LCD.