Modified sine is not exactly a bunch of square waves made close to a sign. A better description is a jagged sine wave. Instead of being smooth, it is like stair steps up and down.
Modern PC power supplies have absolutely no problem what so ever with modified sine wave.
It is true that noise can be a problem with an inverter, but if you know what you are doing, and do a proper wiring job, it often is not an issue, or can be minimized to at extent where it is not noticible. There are some vehicles that are just plain noisy, and using a DC-DC PSU is the easist solution.
goosey2099, don't bother posting if you are going to use language like that, and don't spout crap without giving anything solid to back it up. We don't like flamers in these forums.
Recently a user in these forums posted who is slightly dissapointed in the Opus. Largely from reading posts about how it is the best, etc. he made the decision to purchase it. Now he's found it won't even power up his PC, which was only 1.3ghz. He had to underclock a Celeron 1.3GHz to power it! At least with an inverter he was able to run it at full speed! Plus he is having other problems, such as are know to happen with Opus 150w.
All I'm getting at is: KEEP PERSPECTIVE! Opus doesn't work for everyone. I'm not saying an inverter is the best, but IMHO, neither is OPUS.