Quality Security Software - Which one?

I need a program that can secure files / drives by making them invisible & protected. A bad experience has made me wary of freebies.

Who are the front runners here?

 

I've noticed some people using a program called PC Security from www.tropsoft.com which allows you to protect data.

 

I also use PC Security, mainly because it was so practical. There are alot of similar softwares like PC Security, but they weren't convenient enough.
I lock my data partition[D:] via the PS-icon (right and left mouse-click) and then a password and that's it. I use the same procedure to unlock my data partition.

Locking means : no reading, no writing, no stealing, no access at all to the locked partition. The locking is immediately and doesn't require a reboot or waiting time, like other similar software did.
I also asked the developer to "hide" the partition and he will consider it.
At this moment, the "hide" feature is only possible for folders, not the complete partition.

I lock my data partition, when I do "dangerous" stuff, that might hurt my data partition, like surfing on the internet or trying softwares from an unknown source.
I'm not really afraid of destroying my data, because I have a backup of my data.
I'm afraid of infected data and if I don't see it in time and backup the infected data, everything is infected.