Vista - Please help, unable to install many softwares

Got a new HP Pavilion DV9000 laptop with a Vista Home Premium X64 with SP1 loaded.

Was able to install Office 2007, McAfee Antivirus, MTorrent and Nero.

Not able to install DirectX, Itunes, Yahoo Messenger, Google Desktop, GoogleTalk. Chrome got installed but not working. When installing itunes, getting the Service "Apple Mobile Device could not be installed.Verify that you have sufficient privileges to install system services. I get different messages for different softwares. When trying to install DirectX, my Vista Validation also fails, it says unable to copy the checklegitcontrol.ddl file. I cannot find or copy this file to my system32 folder. I am doing all the installs as an administrator, i right click and use the run as administrator option. Tried taking ownership of all the folders and registry keys with no luck. cant use Windows update as well, get this error 80070005 Please help.

System Configuration:

4 GB Ram
320 GB Hard Drive
512 MB Nvidia GeForce 8600M GS

Possibly you arent using x64 programs....

Was able to install after a system recovery.

Well that sounds like either a virus or something screwed up in windows. The longer windows stays on, the more problems it accumulates... Good job fixing it.