For those of you who have got the blank page on the install.php page, I have found one fix that worked for me.
The problem usually arises when you don't have php errors enabled to show. To fix this, edit your php.ini file (on linux -> etc/php.ini -- on windows -> windows\system32\php.ini) do a search for "display_errors" and set this from "display_errors = Off" to "display_errors = On". Now restart apache. This will allow php to display any errors during install instead of a blank screen.
Now thats only half the issue, you now you get nice fuzzy error messages and its not a blank page (which is good) but it still isn't working. So the next step is to edit your php.ini file again.
This time search for "memory_limit". It should read by default "memory_limit = 8M" change this to "memory_limit = 16M". This will allow php to use more memory to execute scripts (NOTE: this will degrade some performance as php will now use up to 16Mb's on memory to execute scripts, unfortunatly sometimes this is necassary).
WARNING!! DO-NOT PUT A VALUE OF MORE THAN 16M AS THIS CAN CAUSE A LOT OF STRAIN ON YOUR SERVER, DOING SO IS AT YOUR OWN RISK, AND PLEASE CONSULT YOUR HOSTING PROVIDER BEFORE MAKING CHANGES TO ROOT FILES.
I hope this works for you as it did for me.