The big switch...

 Ok, I know everyone's feelings about  Emachines, but the reality is that at work, I am stuck with several of them.  As they are falling apart, we are piecing them together into usable units.  Recently, my very old, but solid, emachine took a power surge.  In the middle of the day the lights in the office shut off, came back on, but my computer would not.  The fan was running and it was trying, but it just kept beeping at me and flashing the power light at me.  (Mother board???)  Since I had some files I was working with on that hard drive, I pulled it out and inserted it into a different unit whose hard drive had pooped out some time ago.  They were different models and each only had 1 hard drive.  Upon firing the second computer up, everything came up right away.  However, since the models are different and it booted up from the hard drive from a different model, there were some hardware/driver issues.  Currently, I have no sound.  I have tried to uninstall the old driver for the different model and install the correct driver, but the computer is not recognizing the sound device at all.  It has a Realtek Internal HD connected directly to the mother board. (Best I can see.)  Nothing seems to work.  Any suggestions?

Also, my networking came right up as I can talk to all the other computers on the network, but I cannot access the internet.  I have had this issue before, but I cannot remember what step I missed then, so I can't fix it now either.

Feel pitty on me and throw me any advice to help fix this.  (Any advice other than toss out all Emachines, that is not going to be an option for me right now.)

Thanks!