The Free version of Prevx is about 1MB in size and is compatible with any Windows versions XP and above. To use Prevx, you need not remove your current security softwares, since Prevx plays nice with other anti-virus softwares. The full version of this software can be bought for 35 USD (for a single user) from this link. We would rather recommend you try the free version first; download the latest Prevx 3.0.5.3 from this link.