Just did this on an old Inspiron 1545 with Ubuntu 12.04 on it and I'm already noticing major improvement in both boot time and the apps I open frequently (also with the help of preloader and zram)

I followed this guide: http://www.howtogeek.com/69753/how-to-cut-your-linux-pcs-boo...

Although note, at the part where it says push CTRL+ALT+F1 to get to a new terminal login, that didn't work for me. I had to go to the default one (CTRL+ALT+F7) and type "logout" and then go to CTRL+ALT+F6.

I have a web page I keep track of common things I do to my Ubuntu installs (shameless plug: http://ubuntu.mindseeder.com) and I'm definitely going to add this so I don't forget!