It may not work at DDR2 800. Its better if you just try to tighten the latencies and check how it behaves. If it clocks higher well and good. If it doesnt tough luck! I wouldn't expect it to clock much either given that it is value ram. You shud have purchased crucial ballistix instead... they are cheap and very overclockable! The best DDR2 is the one based on the Micron D9 fatty chips. (there are two versions of d9.... fatty which does tighter timings and thin chips which dont do tight timings but clock really well) They do 667 MHz at really tight 3-2-2-8 timings at around 2.1-2.2V. (Corsair XMS2 5400UL uses these) The drawback is that they are incredibly expensive. If the chips are elpida and not micron, they'll have zero headroom as they suck for overclocking.
Edit: To find if your OC is stable, use Memtest86.