You have to download a program, I believe.
I was alos disappointed at this, since I wanted to post a game of mine, but had to do it out move by move since I couldn't get the PGN.
Sorry, but I have this same problem! I'm not going to download something from an unknown site to view them...
I use chesscat because it also lets you add annotations. I have also heard of ChessPad ( 
www.wmlsoftware.com ), which (while not the shiniest program out there) has a lot of features for its size. If you want, another option is to open the PGN file with Notepad, select all and copy, and then paste it into an online reader (such as here and a related thread here) and it will play back the game for you online.
It might just be easier to post a game in the forums, move for move, with annotations, and then just copy/paste the PGN.
All the pgn can be opened with a notepad (Choose"Open with..."). They can be opened with the old winboard and/or a chessbase product, if you want to replay them and/or add comments etc.
Yes, I guess it'e the light & free standard.
I admit it, I haven't figured it out. I'm no computer geek. Give me the simple, 5th-grade level instructions on "How to view pgn files". I download the files, my PC tells me it can't open this type of file, I download the free Rybka and the Tarrasch program thing, hoping they can find and recognize and display the pgn files I've saved, and I've failed utterly. I just want to use all the pgn stuff on Chess.com. Can anyone help me out? Thanks.