I've had 0 probes since my IP address is 192.168.0.3 And the router PC is firewalled and running scanners etc. too.

Miriamel: You've likely got the 32-bit one, I doubt you have a high-end several-thousand-$ multi-CPU server, but a normal Pentium 1/2/3/4 or AMD Athlon or some variation, which are currently 32 bit

It's your choice if you install Service Pack 1 or not beforehand, it's not necessary. But it does contain a multitude of other bug fixes and patches for Windows. I chose not to install SP1 on my machine, and have gone for the seperate patches instead, much like the one you're about to download.