After a lot of personal research, straightforward testing, and lessons learned, I came up with the following freeware solutions for keeping my system up and running.

FIREWALL
– COMODO Firewall Pro

ANTIVIRUS
– AOL Active Virus Shield (based on Kapersky)
– a-squared free

ANTISPYWARE
– SUPERAntiSpyware Free Edition
– Microsoft Windows Defender
– SpywareBlaster
– McAfee SiteAdvisor

REGISTRY CLEANER
– Advanced WindowsCare V2 Personal
– CCleaner

ANTISPAM
– SpamBayes

DEFRAGMENTER
– Speedfrag (a bit akward to use at first, but simply the best one available for free)

MEMORY OPTIMIZER
– Cacheman

All those software are free to everyone for personal use, they are also easy-to-use, non-intrusive (almost no pop-ups windows) and low-memory consuming.

My laptop is now booting up in 55s with 659 Mb of free RAM available (out of 1Gb total), and is decently fast.

I consider it good, but I would like to make it even better.. Any advise?