I currently have the free version of Spybot Search & Destroy. I am thinking of purchasing either the home or the professional edition. I am currently using Avast Pro on a two-month free trial, and had intended to purchase same. Are the two compatible? Are there redundancies? Do I need both in order to cover malware and viruses. I am a bit confused as to the capabilities and limitations of the two, and would like some help in making a determination as to what application or combination would best suit my needs. Thank you in advance.