Is it wise to replace an Intel Celeron D with another Intel Celeron D, that clocks Faster?

It'd be better to replace the whole thing. Some benchmarks to show just how out of date that cpu is: http://cpubenchmark.net/cpu.php?cpu=Intel+Celeron+...

However if you're dead set on it, as long as you have sufficient cooling and both chips are the proper socket type, you take care not to destroy any component while swapping them, and have new thermal compound to spread on the new cpu. it would be fine.

Not a good idea. Too old. A modern dual core amd or intel laptop processor could easily beat celeron D processors even with less clock speed.