Yes you will still be able to play Counter-Strike under Linux. Check out www.counter-strike.net for the Linux MOD's.
Fakeboy -- I think that those are only the Linux dedicated server ports. There is still hope, though! To play CS on a Linux box, you'll need to either setup WINE (http://www.winehq.com/), setup VMWare (http://www.vmware.com), abandon Mandrake and install Lindows (http://www.lindows.com -- NOT RECOMMENDED JUST YET.), or make your system dual boot (http://www.linuxgazette.com/issue38/veselosky.html). Any option will work, and I'm sure there's at least one or two other ways to play CS on Linux.

However, this kind of answers your other question, Charmed Rulez. You can have Windows and Linux work side by side at least 3 different ways I know of, and possibly more. Lindows promises to be able to run Windows apps on Linux, but I'm not holding my breath for this project just yet. I think your best bet is dual-booting for now, until you get used to Linux.