At least in gaming I'd say it's well below an XP1600+ or P4 1.6A.... in fact it regularly get's it's ass handed to it in such cases.
In business apps, or 2D graphics design it performs much better thoug, perhaps incrementally faster then the 1.6A and roughly on-par with the XP1600+.
In any case, even heavily overclocked I would MUCH rather even the slowest AXP or P4 Northwood over the Celeron 2GHz.