It's been a couple weeks now since I started using this great OS and I have grown to love it more every day. I make a point to use it for at least 1-2 hours a day because diving right into something new is a better way to learn about it. This approach may overwhelm some at first but once that passes a lot of things start to really make sense.
The built in software is complete enough that I only had the need to add 3 apps to make it useful for all I need to do in daily computing. The apps I felt the need to add are GIMP (image editor), VLC and LibreOffice. Lubuntu/LXDE include Abiword but I have never been a fan. LibreOffice is based on OpenOffice and I find it very capable.
For video playback I really like GNOME Mplayer which is built in but VLC is a must have for me. Mplayer is a bit more efficient but VLC gives you so much more control over your playback so it's a necessity. All my Apple Partition Map hard drives with video work perfectly over SMB networking.
With browsing I have not explored any options outside of the built in FireFox which after updating is at version 15. It's all I need since it's the most capable and customizable browser on any platform. Chrome seems to be the current default browser for the x86 version of Lubuntu and where it sits by default in the task bar is a red circle with a line through it on the PowerPC version as anyone who has tried it will know. I never felt the need to look for a PowerPC alternative on Linux since I much prefer Mozilla browsers.
The experience has not been without growing pains but for the most part it has really sparked my attention. After about 6 or 7 years of playing around with Linux on occasion I am now sold on keeping it along side of OS X and BSD from now on.
You should use the Synaptic package manager to find and install all your apps. The Lubuntu Software Centre is a resource hog and has a less intuitive interface compared to Synaptic in my opinion. LSC has also crashed on me several times.
Based on my experiences you could get by fine on as low as 128-256 MB RAM which is mostly thanks to the LXDE GUI. I say that because I have never seen memory consumption go over about 230 MB and that was with 5 apps running and playing a video. Very impressive for modern software which points to just one of the many best of both world benefits of Linux.
More on this as my Linux journey continues.