Yea definatelly this memory is good choice. I doubt you will see speed difference between 3200 and 4200 - usually bottle neck in computer is speed of hard drive and CPU. What you using your computer for? If games - invest in good graphic card and additional memory, if office work, I belive configuration you have now is enough Also good thing to do is to reinstall system on computer - you can be suprised how fast clean systems are Get rid of all not necessary residential programs like antyviruses (1 is enough) or firewalls (who would need one anyway unless you are CIA agent ).
I'm using 3Com router, which is filtering strange connections with his built-in firewall, also sitting behind masquerade, so it is not that easy to identify my computer directly. Trying to keep common sense in finding cracks and stuff, also limiting myself in watching net porn (prefer rl one ) so my system is kinda fast even if my computer have 3 years old parts inside You can also consider recovery card - browse on ebay for those - costs like 30 pounds maximum and do all antivirus and firewall jobs