depends if its p4 celeron or tualatin celeron.
tualatin celeron might actually run faster than the p4 on the low end p4 side (the newest celerons were all 133 bus with 256k cache, just like a coppermine, so compared to a p4 1.5 or 1.6-1.7 laptop a 1.2 celeron wouldnt be bad).
i think the celeron-128 p4 based out like the 1.4 and 1.5 might not be a good choice, as memory speeds on laptops tend to be ddr200 not ddr266 etc, and the less cache will really hurt it compared to a 512k cash p4-m or northwood desktop based laptop with also 512k cache because of latency issues. basically the same reasons as for why the celeron p4 on desktops isnt that great either but maginified because of ddr200 and not ddr266 on some of these systems (i know the dell inspirons only run at ddr200). basically any p4 will own a celeron (i.e. a celeron 1.8 is slower than a p4 1.4 williamette in desktop benchmarks, and would be more so than a p4 northwood in say a laptop . so a celeron 1.4 128k laptop cpu, probably would get toasted by any p4 and most p3-850-900mhz class CPUS, except on floating point for the p3s )