Some Weird Virus

A couple of weeks ago I was sent a file over AIM (Instant Messaging Service). Stupidly enough, though I didn't know the person I accepted and opened the file. I didn't think there was anything malicious about it since my Virus Program scanned it and nothing was found. So I opened it and a message soon appeared saying "Your trial of Obsidium is over." I have no idea what Obsidium is and I never installed it, so I simply closed the warning box and forgot about it. However, the next time I booted up the machine I tried to login and the computer hesitated, the same Obsidium message came up and another message appeared in the top right corner appeared which said Systeminfo32 (I think that was the name of it) was trying to update itself. I pressed CTRL ALT Delete since my system was now at a halt, with only the two boxes appearing to make progress. Under Processes in Windows Task Manager I saw a program I could not recognized called "system32:systeminfo2.exe". I closed it immediately and I was able to proceed and everything was fine. However, now this occurrence happens every time I start up my computer. I searched for "system32:systeminfo2.exe" on Google and I was unable to find any good information. Can some one help me out. I have even tried using MSCONFIG to disable the EXE on the startup, but it just comes back every start up. I even tried using Hijack this, which is like MSCONFIG, but has more you can disable such as Browser Add-ons and such, but I had no luck. This is a pesky little virus, and though I have no information whether it is eating away at my System's internals, it could be. I tried to find "system32:systeminfo2.exe" so I could delete it, but even running a search left me unable to trace it. Any advice or help on this subject, so I can successfully remove this problem. Also, what kind of virus scanner would you guys recommend.