There are lots of tutorials on Remote Assistance. Here's a very detailed one:
http://www.petri.co.il/what%27.....istanc.htm

Most problems that I have seen are due to routers or firewalls blocking traffic. Use of a VPN, as mentioned in the linked article, can eliminate problems with NAT traversal (crossing a router). However, if a VPN is not available, port forwarding through the router may do the trick.

If the built-in Windows Remote Assistance is not required, try CrossLoop which uses VNC to create a VPN for remote viewing and control. It's very easy to use and has no trouble doing NAT traversal. See these instructions by The Geek:
http://www.howtogeek.com/howto.....-easy-way/

Yes, CrossLoop performs the same function as Remote Assistance, but using a different protocol. It's very easy to use and, with the permission of the remote user, you can control the keyboard and mouse of the remote machine. By creating a VPN, CrossLoop eliminates the need for port forwarding and has no trouble with NAT traversal.

Have used CrossLoop with my brother-in-law quite a bit and no problems whatsoever (and ScottW helped me take a shakedown cruise with it when I first started to use it). The only thing I would add is to make an IM connection with whoever you're going to help FIRST (and you need to get the "secret handshake" . . . access code . . . from that person anyway).

When my brother-in-law and I do a session, we connect via IM (WLM is what we use) first, he gives me the secret handshake, and off we go.

Read the HTG discussion ScottW linked to (the Geek wrote it and it's done well), though instead of "Join" and "Host" tabs it's now "Access" and "Share".

If you're going to be the helper, you'll enter that access code in your "Access" tab, and the "helpee" will give you the access code ("secret handshake") from their "Share" tab. Then you press the "connect" button and tell him/her to press "connect" and accept your access when it asks, and you're off and running.

I have no idea about the microphone or webcam, but as far as the "text box" goes, that's why I suggest an IM connection too. CrossLoop doesn't do anything else but connect you to the host machine. As I recall, the Windows RA does have a text box, but then you would have the problem with the "port forwarding" stuff and NAT traversal.

So, on the one hand Windows RA I think provides that "text box" you spoke of but it has problems getting through a firewall, while CrossLoop doesn't provide a "text box" (which is why I suggest to supplement it with an IM connection) but goes around firewalls and is easy to use.

My vote is for CrossLoop.

If all else fails, you can also try LogMeIn.com

It works great.