If only credit cards but not banking accounts are stolen, then your computer may be okay.
Credit card info could get stolen in many ways, and there is no simple way to completely prevent it.
BOA provides credit card with free security warrantee. If it is stolen, the bank refund all your money rightaway without asking you much (just identify which was not your purchase). I use that for all my online shopping. Practically, the bank monitors its security status and changes it quite often (mine has changed 3 times in last three years).
