So I did follow the steps outlined in this site to uninstall previous versions of Visual Studio 2008 as I have installed the beta versions previously. While running the installation program after the cleanup, I encountered the error telling me that Visual Studio Asset System is still installed. I checked high and low searching for the Visual Studio Asset System on my Add/Remove Programs but couldn't find anything. A post on the MSDN Forums helped me fix this issue. Rename these registry keys using Registry Editor
I just appended _old to both key names and my installation worked like a charm (of course, modifying your registry comes with your own share of risks, if you know what I mean)
And just for the record, the installation of Visual Studio 2008 wasn't just a "walk in the park." I get these "DepCheck indicates Microsoft .NET Framework 2.0a is not installed" errors when I tried to install .NET Framework 3.5 manually. I tried doing this since Visual Studio 2008 installation could not proceed even though I've managed to go thru the selection on which components to install. I ended up uninstalling .NET Framework 2.0 and did a couple of reboots. I even checked if I have Visual Studio 2005 Service Pack 1 and .NET Framework 2.0 Service Pack 1 installed before going any further but no luck. Once .NET Framework 2.0 was uninstalled, my Visual Studio 2008 installation went fine. I wish Microsoft would fix this for those people having Visual Studio 2005 prior to installing Visual Studio 2008.