Question about playing The Sims 2 without a CD?

Ok, so I bought the 4 disc Sims 2 game a few years back and played it fine on my computer for a long time. Recently I decided I wanted to play it again, but I couldn’t find my University expansion pack disc anymore. So what I did is uninstall the entire game from my computer and try to reinstall it with just the base game.
It wouldn't let me play it however, as it was saying something about permissions errors. Long story short, I uninstalled it, made a disc image and put it on an external hard drive so I could install the game on my newer laptop (which happens not to have a disc drive, gr).
Everything installed very smoothly, but now I'm running into two different problems, and I was hoping someone could give me a hand on one or both of them

1. I now can't play the game without inserting the disc, even though I still have the Images on my computer. This is a problem because I don’t have a disc drive on this computer :/ I read something about mounting the image? But I don’t know how to do it, and I was wondering just how safe this is? I don’t want any viruses...

2. I need to install the update/patch I got from the website, because I think it will solve some compatibility issues with The Sims 2 and Windows 7, but it's telling me to put disc 4 into the computer. Once again, this is a problem because I don’t have a disc drive lol.

So if anyone could help me out on this, it would be much appreciated! Thank you!

 

What you need is magic disc... http://majorgeeks.com/MagicDisc_d6761.html
Once you install it, go to your .iso file. Right click and there will be a new little thingy that says magic disk>set number of drives>1... then back to right click on image, mount image to x:/(or what ever letter you assigned your virtual drive)
I'm not sure however, how it will work.
As far as viruses go, anything you DL here on MG is verified and trusted.

 

You can also share your CD drive over the network. My question though? How did you install it without a CD drive?