OBSLF - you are quite right, we don't have enough resources to police the ills of the whole world but should that mean we shouldn't do anything at all anywhere?
And how do we decide which to get involved in? Darfur? Congo? Uganda? Zimbabwe? Sri Lanka? Kashmir? Colombia?
Why should we go into the Congo and not Darfur? Why should we go into Zimbabwe and not Sri Lanka?
Undoubtedly, there are at least 10x as many conflicts ongoing across the world. There are conflicts in all of those countries with the resulting terrible suffering. The UK and the US are already overwhelmed with their current commitments in Iraq, Afghanistan, and elsewhere. The US economy is circling the drain. Our deficit spending is catching up to us.
Yes, there is terrible suffering in the Congo. It would be very difficult to stop. It would require a large number of troops (that we don't have) at the end of a long and difficult (read: expensive) supply line. Neither the UK nor the US can afford to intervene. Neither the US nor the UK have strategic or environmental interests at stake.
If we have learned one thing over the past 7 years, it is that there are limits to our power. If we are going to intervene militarily, we need to go in hard and fast, with overwhelming power. Doling out 5,000 troops here and 10,000 troops there for open-ended engagements in un-ending civil wars is the height of folly.