Thread is useless without the spec of what you have at the moment mate. That or a budget for a new machine.

My basic rule has been fast memory, more fast memory, quality graphics then CPU. Disk is going to be less important once you start playing as games tend to cache the details for a map or level before you start.

If you can get a ADSL Router and get your machine upstairs wired directly to it along with your parents machine. In my experience 'Internet Connection Sharing' can add up to 30ms to your ping times. Was great when I had an ISDN line and everyone else was on Modems but not anymore.

And no, I weened myself off the games years ago.