Yes -- I know this thread is old (I am the Thread Digger, after all ), but I'm interested in knowing how this worked out for you. Did you end up getting that?
If I had seen this earlier, I'd have recommended that you open the wallet a bit. My mom has a Pentium 4 3 GHz (not sure of the L2 cache), 3 GB of RAM Intel 915G chipset. With newer Ubuntu releases with the Unity interfaces, I'd say it's acceptable, perhaps on the verge of needing replacement, even though all she does is surf (Facebook included). Each webpage takes a few seconds to load. I saw Ubuntu run on a configuration similar to yours and it was not pretty... everything lagged bigtime, and I wouldn't consider it usable and I consider myself fairly patient with slower computers.
Also, on my own laptop (with an i3-350M and 3 GB of RAM), installing the 64-bit made a huge difference in overall snappiness, so I'd at least go for one of the rare P4s (like my mom's) that's 64-bit, and 2 GB of RAM.