Advice Pro :
How do I subscribe to a thread without contributing adding a post?
Just click on the email notification button when it has no X. You can't flag a post you haven't responded to, although it will get an automatic red flag to show that you've read it. Instead of flagging it you can add it as a "favourite" or "bookmark" (the heart button) and it will show when you click on the "Show my favourite topics" button on the forum home page.
Advice Pro :
And what's up with the first link in this thread:
http://www.tomshardware.com/forum/234399-49-close-computers-aware
That thread is from 2007, when the forum used a different URL (forumz.tomhardware.com). Those old links no longer work.