If you're going to go with a remote access solution (which takes control of another computer), GoToMyPC with their recurring $20 monthly charge is one of the more expensive options.....by no means the cheapest.
Windows XP Pro has remote access software already built in.
Other good options include Famatech's Remote Administrator -
www.radmin.com - which costs $35 (for the price, you'd be hard-pressed to find a more secure remote-access program), and Symantec's pcAnywhere -
www.symantec.com/pcanywhere/Consumer - which goes for $200.
If you're doing remote access within a LAN, VNC -
www.realvnc.com - is excellent, by far the most widely used, & best of all free.