what are the ways to align conditions in cases

For example, the following is not very nice:

[f(x)]_N=\begin{cases}
f(x)  \text{       if } f(x) \le N, \\
\newline N  \text{     if } f(x) \gt N.
\end{cases}

How can I make it nicer?

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Welcome to tex.sx! A tip: If you indent lines by 4 spaces, then they are marked as a code sample. You can also highlight the code and click the "code" button (with "101010" on it). –  Caramdir Apr 15 '11 at 22:46
Thanks, Caramdir. –  Qiang Li Apr 15 '11 at 23:08

$[f(x)]_N=\begin{cases} f(x) &\text{ if } f(x) \le N, \\ \newline N &\text{ if } f(x) > N. \end{cases}$