My first thought is that your Windows 7 Machine is missing the following update/install package, Microsoft Visual C++ 2005 SP1 Redistribution Package. This assumes Windows 7 32-Bit. Reboot, then try the install of Access i again.
Are you installing all the components of System i Access? If not, which ones are you attempting to install? Is this an initial install of the application or patches being applied to the System i software?