The 2gb problem solves some peoples Vista installation problems, so certainly try reinstalling with just 2gb. If that works then put the other 2gb in after installing SP1, or after installing this hotfix.
If that doesn't work then you may download the Intel RAID drivers and load them at installation to see if that helps.
If that doesn't work then you may download the Intel RAID drivers and load them at installation to see if that helps.