I have a Windows, but I want have a Linux. Can someone show a good one? (I prefer
a text-based Linux...)

One option could be a dual boot system, where you can choose between windows or linux during the system inicialization. I like Ubuntu, but there are other options ...

About dual boot I did already know, I just wanted know about a good linux... Uhm... Ubuntu does takes too much memory? My computer dosen't have much memory free...

Not too much .... I run Ubuntu in my computer with 768 MB of RAM, and it is enough for me .. But the recommended minimum memory requirement is 384 MB of RAM

Ok...

Slackware or SuSe for me. Otherwise OpenBSD.

I have Debian on a 1GB "disk"/128MB RAM embedded system with a 200MHz Geode processor (mainly as mail- web and cvs server). Works nicely (as long as not too much spam arrives and spamassassin uses all the CPU power).

(I prefer a text-based Linux...)

Do they also have sound-based distributions now? Really, what's that?

OpenBSD is nice and all, but I wouldn't use it as your first *nix. You really have to spend *lots* of time to learn the basics before you can do anything with it (secure by default means: switched off by default. So before you don't know how something works, you can't switch it on, and therefore can't use it. Great idea, from the security point of view, but you prtty fast get stuck and frustrated. Don't get me wrong. I like OpenBSD and its policy. But as I said, I wouldn't use it as a first *nix system)

As a first go at Linux, I think Ubuntu would be a good choice.