should I use 64 bit ubuntu on intel core2 t5500?

[Janina Sajka]

I now have two Intel dual-core systems that are running Fedora Linux
with relatively few problems. One is built on an Asus Pundit P3-PH5 board which I equipped with an Intel 6600  running at 2.40GHz. 
The other is a Thinkpad X61 which I purchased with an Intel T7500
running at 2.20GHz.

On the other hand, I've had nothing but trouble with an Opteron based
system based on a Tyan Mb that I put together back in 2004. That system,
which I put a lot into, is now just off-line, looking more and more like
an overgrown paperweight. I've never been able to get a handle on why
this system has been so unstable. It seems to be heat related, but even
massive fans aren't helping. And, the nagging thing is that it can be
stable for months, and then suddenly not stay up for more than an hour
or two at a time.

Janina