Another option is a xBox 360 connected to a hdtv with a hdmi cable and a xbox live account. You put the video file on a portable usb harddrive and plug into the xbox (must be a FAT32 formated drive). Navigate to Videos > Portable device and play the file.
This is the same way I've been doing it all season. If you're new, then you probably either:
a. don't have a powerful enough pc
b. don't have the right software
More than likely it's the software.
Make sure you have the CCCP installed (combined community code pack). google it, it's free
Also make sure you have Media Player Classic Home Theater installed to play it (or VLC) after installing a codec pack and it will work fine if you have a near modern pc.