It's an interesting site. Not sure I agree with it all. For example, it says 95% for 4th gen test at 4 weeks.
I've heard that exact number for 3rd gen tests.
And if 95% was the number for 4th gen test, as it says,
why would UK, many states in the US now, many other countries in South America consider it conclusive at 4 weeks? Even the CDC has (according to AIDSMAP) said its good after 4 weeks.
But it does seem to have some other good information.
Be well
I was not previously aware of iBase. On quick review of its home page as well as the links provided by matthew589, it appears to be a high quality resource, based in the UK. However, it is designed primarily for HIV infected people with questions about treatment and living with HIV/AIDS, not those who have been exposed and are concerned about becoming infected. Still, it has accurate information about how HIV is transmitted -- and most important for many users of this forum, how it is NOT transmitted, e.g. by kissing, body contact, exposure to most body fluids, and so on.