Did you make sure nothing (including antivirus or firewall) was running when you installed them? When you say "half the games stall out during install", is there a something in common with the games that fail as compared to the ones that work (i.e. are some those Windows compilation CD's, some old DOS, etc.)
As much as I am sure the game developers have troubleshooting FAQ's on their websites, it does seem strange that both you and your friend are having the same trouble.
Another avenue to explore - are you certain that your PC meets the the game requirements? Putting aside processor speed and RAM, HP's are know to use SMA which allocates system RAM for video instead of a dedicated graphics card.
Consider these suggestions and then post more specifcs about your computer and what the error messages are.