The problem with most of these polls is that they are not specific enough (but the vagueness creates controversy and makes things interesting).
Is 256 ram ALWAYS enough? Certainly not. Is 256 ram usually enough? Mostly, yes, but it depends...
In my opinion, a computer should generally have at least one meg of ram for ever 4 megahertz of processing power i.e. 256 megs for a 1Ghz CPU, 512 for a 2Ghz, but that's just in general. For many users, especally business apps, 1Ghz is already more than enough speed, and in that case, 256 RAM is also more than enough.
On the other hand, if you are a power user, you might want to have 1 meg for every 2 megahertz of CPU power.
Certain applications simply need the RAM even if you have a decent CPU. Photoshop, 3Dstudio max, any kind of video editting... RAM is critical, so for Audio-video pros, they should have a 1:2 ratio. For other uses, 1:4 should do. For gaming, extra money maybe better spent on a better video card or CPU power rather than getting the 1:2 ratio.
The thing to remember is that that as long as you have some headroom for your RAM, the CPU doesn't have to go to the harddrive, which is by definition, much slower than systems RAM.
However, unless you are running mission critical software, I would recommend using a RAM defrag program such as the one in CPCool that frees up RAM that is holding a closed program in memmory.