transferring game data between pcs? (plz help)

Hi, I've been working on this problem for a couple of days and am beyond frustration. I'll include all my steps in trying to solve my problem. Hopefully someone out there can help me.

I recently stored .iso files of Bioshock and COD4 on my college laptop. I now want to transfer these files to my more powerful desktop comp while I'm home for the holidays. What I attempted first was to transfer the files to my external hard drive and then from there transfer it to my desktop comp. An error pops up saying that there is not enough disk space (even though there is > 30 Gb both ways). Then, I tried transferring a compressed version of each of the .iso's. Same error. Then, to bypass the error, I extracted the .iso's and tried to transfer them. Success.

Now, my problem is basically trying to get the files back into their .iso state so I can mount them into my virtual drive. I tried several programs (like Evolution from complexnt.com) and did get the files into an ".iso" but...it seems that all it does is copy the directory of files and subfolders and renames it into an .iso. So when I mount this and then click on my virtual drive, I don't get the game to pop up. I just get the directory to open into an explorer-like list of the same files and folders. Does anyone know how to reverse the .iso extraction process so that the extracted directory becomes a true unified CD-image?

I'm also thinking of buying one of those A/A usb cables for direct transfer, but those are quite expensive and I'm not 100% sure it'll work (since the transfer to the external didn't).

Someone please help me out. I just suped up my desktop for Christmas and I'm dying to test it out. If anyone needs clarification on anything, just ask. Thanks