Should I worry about Spywares and Malwares

There are many threats other than virus in the system. I would like to know if I have to really care for them. What is the threat rate and how well is the protection? I do pay my bills online where I enter critical data. Isn’t basic Windows sufficient? There are many software for the functionality. I am simply confused to choose from many available spyware and malware removal programs. Can anybody guide on best software for the same? Also, it will be of great help if anybody can help me on steps to find out whether given system has already affected by spyware and malware
