I always use a wrist strap when I build my computers. You can buy one for $5.00 and personally I don't think it is worth the risk. I just had an incident the other day working on my computer I neglected to wear the wrist strap, I just touched the metal case to ground myself but somehow and I am not sure if this was static related, but I corrupted the chip on the motherboard. If it was not static I don't know what it was because I accidentally touched my board while I was dusting my case. I also use an anti static mat.