If you are sharing your connection and need to print or send a file to a PC on your network, then "G" would be great. If not, don't bother.
If you are playing online games in which ping times count, then you may have a reason to change. The speed can help.
I'm running Windows XP Home, I have dsl and my service is 1.5 mbs download max and upload 384 kb. Would it be worth it for me to upgrade to G? I am not sure. Any help would be appreciated. Thank you.