I know how you feel; I tried so many different distros before getting a feel for the differences, and I continue to try new ones, usually in a virtual machine or a spare partition.
I don't really find Gnome to be slow and bloated, but I'm not too happy with the direction it's gone recently with the Gnome 3 shell. Gnome is fairly simple compared to KDE, but not nearly as customizable, and it's getting less customizable, it seems.
I find KDE to be overkill, and I've never spent enough time to feel comfortable with it. It has lots of options, widgets, etc, and of course, some people love it for that. KDE may also have the most variety of (native) apps available, but I haven't used it enough to really know.
From your post, i think you should look at XFCE. It's the least bloated of the mostly full-featured environments, without a lot of extras. It will run most of the same things that Gnome runs, as it uses the same GTK toolkit, I think.
However, it's possible to run KDE apps using Gnome, etc, buy you need to also install whatever supporting libraries, etc are required for them. A lot of people don't like to do this, but if you have plenty of disk space, it's probably fine.
Being new, I'd recommend sticking to a mainstream distro like Fedora, Ubuntu, Debian, etc, as 3rd party software is more likely to have an easy install for their programs.
I should add that this is all a matter of opinion more than anything else, unless you add some more criteria that might differentiate the differences more.
From the GNOME3 FAQ in the ArchLinux Wiki:
excerpt
Gnome 3.10 UI elements scale incorrectly
With 3.10 Gnome introduced HDPI support. If your displays EDID info does not contain the correct screen size, but the resolution is right, this can lead to incorrectly scaled UI elements. As a workaround you can open dconf-editor and find the key scaling-factor in org.gnome.desktop.interface. Set it to 1 to get the standard scale.
UPDATE #1
The OP provided the following info regarding the monitor.
It's a Philips LCD SXGA17", specifically It says 170B7CS/69
After a bit of research I found these 2 URLs for that product family.
AUTO
This issue if not resolved by the above method of setting the scaling-factor, may be an issue of the monitor not correctly adjusting its overscanning correctly. You can typically force a monitor to auto sync, usually through the menus on the monitor itself.
Based on the manual this monitor has an AUTO button which might resolve this issue.
Compatible modeline
You can confirm that your video card is using a compatible resolution for this monitor. Again according to the manual the following is recommended.
Recommended video mode for Philips 17": 1280X1024 @60Hz
You can confirm this is what you're driving the monitor with using xrandr.
$ xrandr -q
Screen 0: minimum 320 x 200, current 1440 x 900, maximum 8192 x 8192
LVDS1 connected primary 1440x900+0+0 (normal left inverted right x axis y axis) 303mm x 190mm
1440x900 60.0*+ 50.0
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)
Make sure you're driving it with the correct interface (VGA, HDMI, etc.) as well. The above output is from my Thinkpad T410 laptop, so your's will be different. You'll want to make sure that your resolution is being driven at 1280x1024 @ a 60Hz refresh rate. The line with the star (*), tells you which mode is currently in use. This is what my default is:
1440x900 60.0*+ 50.0
Best Answer
Given your use case, and if you are this low on memory, the best choice would be to switch to a lightweight Desktop Environnement (DE), such as:
If you are (even sort of) new to Linux, I would suggest you to stay away from Tilling Window Managers (TWM); although being extremely lightweight and powerful once configured and mastered, I do not think one of these would be a good idea given your situation.
If you want to install XFCE (example):
First, you need to add the Extra Packages for Enterprise Linux (EPEL) repository, as this is where you will install packages from:
Then you can install XFCE Desktop Environment as following:
After a reboot, you will be able to switch to XFCE4 instead of using GNOME3 at the login screen.