It sounds like you've performed a partial-restore? (rather than a full-recovery, which would have erased all data that you've added since purchase)? If not, what procedure did you use?
It also sounds like Windows XP is running OK, with the exception that you are having trouble locating the correct drivers for the motherboard? Take a look inside the case, and see if the motherboard is the FIC K8MC51G (or has an eMachines sticker on it with part # 105554 [the other possibilities are: MS-7207 #s: 105551 & 4006127R / and Foxconn C51GU01 #: 4006111R]. Or try running Everest (not sure it will detect OK with the drivers that you are missing) --- http://www.softpedia.com/get/System/System-Info/Everest-Home-Edition.shtml
Once you know what motherboard you have, install the drivers from the motherboard manufacturer's website ---
FIC K8MC51G --- http://www.fic.com.tw/product/motherboard/AMD/K8MC51G.aspx
MS-7207 also known as K8NGM2-L --- http://www.msicomputer.com/product/p_spec.asp?model=K8NGM2-L&class=mb
Foxconn C51GU01 --- http://support.gateway.com/s/MOTHERBD/FIC/105552/105552nv.shtml
(Gateway owns eMachines)
I seriously doubt that you received a virus through Microsoft. More likely, you may have been a victim of a "phishing" attack - where the attack was made to look like it came from Microsoft. Once you have your system back up and running, make sure you have your firewall, antivirus, and antispyware set to protect the system at all times, and on "high" security settings. If you'd like some recommended tools for that - a good combo might be something like ZoneAlarm/avast!/AdAware/SpyBot. All of those tools have free-for-personal-use "home" editions.
Best of luck
. . . Gary
[P.S. --- and run a few more scans once all is working again. Double-check your local scanners with an online scan, and run a scan for rootkits as well. If you need a tool for scanning for rootkits, try Rootkit Revealer http://www.microsoft.com/technet/sysinternals/utilities/RootkitRevealer.mspx