However, I think like many people here, I haven't seen any difference between the old program and the new. When I go to Utilities to look for QT Pro, I only see QT7.
Think of it as working something like a car. If you have the correct key, you can unlock the car, get in, start the engine, and dricve it around. But whether the car is sitting in your driveway or being driven across country, the name of the car doesn't change.
When I open QT7, I don't see any new feautures or anything that tells me I now have Pro.
As with the car analogy above, the unlocked and open car does not drive anyplace on its own without a driver behind the wheel. Did you have a file loaded at the time you where looking for the availability of "pro" features? QT 7 Pro, lake most software applications, is "context adaptive." This means that the features and menu options may vary depending on whether or not you have a file loaded and whether or not the file is playback compatible, conversion compatible, or edit compatible with your system's current codec component configuration. (I.e., your car will not run without fuel and the fuel must be compatible with the type of engine installed in your car.)
When I go to open an MPG file (the reason I bought Pro), it says it's not a video file and won't open. The only thing I am sure about with QTPro is that it cost me $32.
What am I missing?
Like many users, it would appear that you did not fully read and comprehend the product description before buying the QT 7 Pro key. Keying the QT 7 Player for "pro" use unlocks access to editing features already embedded in your Mac OS X QT structure. IT DOES NOT INSTALL ANY NEW CODECS! This means that files that won't pay in the free QT 7 Player will continue to not play when the player is keyed for "pro" use.
If you read ARTICLE HT3775, you can see what media formats (file, audio and video types) are supported natively by the various current operating systems. Further, if you read ARTICLE HT3526, you will find an abbreviated list of additional third-party media formats and the codecs required to support them.
MPG is a file type and may be used with different audio/video compression formats. For instance, on a Mac it is commonly associated with "muxed" MPEG-1 audio and video formats but may also contain a combination of "muxed" MPEG-1, MPEG-2, or MPEG-4 AVC video with MPEG-1, AC3, PCM, or I believe DTS audio. And, while QT 7 natively supports MPEG-1 video, it does not natively support MPEG-2 video whether in a multiplexed, elementary, or transport data stream. (I.e., you need the QT MPEG-2 Playback Component installed for QT 7 to support MPEG-2 video content.) In addition, since "muxed" file formats are based on spatial synchronization technology (blocks of video data interspersed with blocks of audio data in a single data stream) and QT is based on the use of multiple tracks of data synchronized temporally, "muxed" file formats are, at best, only "playback" compatible with QT 7 Pro editing features. (I.e., QT 7 Pro cannot convert nor edit these "muxed" formats properly if that was your original goal in purchasing a "pro" key.)
Basicly, had you posted to this forum regarding how to support MPEG-2 MPG files, you would have quick learned that the normal approach is to download the free MPEG Streamclip app as an alternative to purchasing a QT 7 Pro key and spend about $20 for the QT MPEG-2 Playback component. This combination provides playback, demuxing, conversion, and editing support for MPEG-2 MPG files. And/or if you prefer to do your editing in QT 7 Pro, you could simply demux the MPEG-2 content to elementary M2V and AIFF file streams that can be editied/composited by QT 7 Pro.
Another approach would be to convert your MPG file to MP4 or M4V files that would then be fully compatible with QT 7 and/or QT 7 Pro without need of additional codec support. I normally prefer HandBrake here since it supports use of the open X264 codec which sports many features that allow you to customize your encoding strategy for QT H.264 use. (E.g., I like to create anamorphic encodes of MPEG/VOB files that include both AAC and AC3 DD5.1 audio and chapter tracks (if source data available) for TV playback compatibility.
In short, there are numerous possibilities for the handling of "muxed" MPEG-2 MPG content depending on your specific goals. Some are free and others require the purchased of add-on components and/or editing keys. I personally consider purchasing a QT 7 Pro key a good moved for any user that contemplates editing files at the track level without having to purchase a full editing application costing hundreds to thousands of dollars. QT 7 Pro is a wise investment for those who know how to properly use it and want to save money making quick, manual edits not requiring specialized routines to be built into the editing app itself.