Somebody may have already referred to this already (I haven't read the whole thread) but here's what Joanna Bourke says about false rape allegations vs convictions in The Guardian CIF:
In fact, false accusations are very rare. The most reliable statistics come from a major UK Home Office research project from 2000-03. Initially, the researchers concluded that 9% of reported rape accusations were false. However, on closer analysis, this percentage dropped dramatically. They found that many of the cases listed as "no evidence of assault" were the result of someone other than the victim making the accusation. In other words, a policeman or passerby might see a woman distressed or drunk, with her clothes ripped, and report it as a suspected rape. When the woman was able to provide an account for what happened, it proved that no rape had taken place. Once such cases had been eliminated from the study, only 3% of allegations should have been categorised as false.
Contrary to the notion that men are at risk of being falsely accused of rape, it is much more common for actual rapists to get away with their actions. Only 6% of offences reported to the police result in a conviction on the full charge of rape. Between half and four-fifths of sexual assaults are never even reported to the authorities in the first place.
Figures for false allegations of rape are apparently no higher than they are for false allegations made about any other crime.
And the vast majority of rapists get away with it, as Joanna mentions above.
So statistically, if it's a "his word against hers" scenario, then the victim is far more likely to be telling the truth.
I expect the point's been made many times, but clearly from some of the comments that have been made on this thread, it needs to be made yet again.