I've had Reformat problems

I recently had a virus, i think it was adriss.exe. I was tired of it so i decided to reformat my computer. I partitioned 2.5 megs for drive c:\ and put windows on it and the rest i put onto d:\ and reformated it aswell. I brought zonealarm setup over with me on a burnt cd disk and installed it after windows was installed. My problem is so far i've had 120 blocked intrusions since i reformated and I'm wondering why and if that's normal. And My cpu usage still fluxiates alot, it been up around 95 sometimes and spikes back down. I'm wondering if this could have to do with my drivers? the virus still lingering or what. Any help would be appreachited, I'd also like to know if firefox is more secure than ie explorer and what I should do to my computer to keep it safe, now that i feel it's safe. I'm don't think all my drivers are installed yet, it seems my disply driver isn't or atleast my 3d card or something, the graphics seem alot worse even on just IE exploerer and such. Any help as to where i could the drivers i need would be great, it took me long enough to figure out ipconfig to setup my dns again properly. thanks