i am a semi-newbie. can someone please suggest me distros aimed at security but easy to install and manage by semi-newbies?

Sorry:

SECURE, EASY TO SETUP, LOW MAINTENANCE

pick any two before you procede.

There is no, and will there never be, such a distro you are looking for.
Being secure is not easy. I don't want to say beginners should not take an attemd at security. But it is very complex to run a secure distro, and still be able to do everything you want.
Everything comes at a price.

So, the question is: What do you want?

I'm afraid that your stated goals may be mutually exclusive. Any distro (including *cough* Windows) can be made more secure. Unfortunately, you are going to have to have a certain level of base knowledge (or the desire to learn about them) about what constitutes a security risk and hot to mitigate those risks. I mean, security starts with an assessment of what you need your desktop / laptop / server to do, and determining what services are turned on by default after doing an install of the OS. I mean, if you aren't using your laptop for web development, then you probably don't need to be running Apache / MySQL when you boot the computer up.

All distrobutions offer a way of monitoring and changing which services are started at boot-up. Some offer a graphical user interface, like RedHat/Fedora or SuSE. Others require you to use the command line interface and change the execute permissions on services, like Slackware.

To actually answer the question you asked, in my opinion, the only distro specifically designed with security in mind right out of the box is OpenBSD. However, OpenBSD operates on the principle that less is better. You start out with a rather spartan installation and you add in packages one at a time that you would normally use in daily operation. I'd hesitate to seriously recommend it to a newbie though.

Personally, I find Slackware to be a nice compromise between the two worlds -- then again, I don't mind working with the CLI. Some newbs might find that too daunting as well.

I agree to what huibert.alblas and Tino27 have said - but if you'd like to learn, there are at least some small and security "enhanced" distros like Trustix or tinysofa that come close to what you'll find if you use OpenBSD, but at least it's still Linux, and at least tinysofa is very easy to setup and uses apt-get, so fine tuning is easily possible. But the story doesn't end there - I think that's the most important point, Tino and huibert have said it all...