I really appreciate your replies! that is helping me a lot to decide
I'll share the specs of the laptop and look forward to your comments:
It's an IBM Thinkpad T40, Pentium-M 1.5Ghz, 512MB, 40GB Hard Disk.
Two months ago I installed Mint LMDE+Gnome on it, and, for example, having 1 nautilus window open + Chromium (3 tabs open) + Thunderbird (2 mail accounts) + Skype; really slowed down the computer, trying to refresh one of the Chromium tabs resulted in a hard disk intense activity (thereby freezing the computer) and I had to wait about 4-5 minutes until the hard disk stopped reading/writing for the computer to respond again. Then I had to close some of the applications to free up some memory.
I really love the LMDE edition (I have it on my desktop computer) but I believe I will have to install a lighter Mint distro on the laptop; now I'm searching it and hopefully install it once I dedide which one to use.
Your opinions are very welcome.