The new SimPE
It took us a while, but now we proudly present the new SimPE GUI. (see this Thread for some Screenshots) 
The main advantage of the new GUI clearly is, that you can open more than one Resource at once with it. And that almost all Elements of the Interface are now Dockable, which means you can put them into the Position you want, or even move them to a second Screen.
The Increased Filesize for the Setup is not due to the new Interface. We included two Manuals (The "SimPE Introcudtion" by Emily and "SimPE - from the Ground up" by TazzMann), which explain some of the basic SimPE features (like the docking).
We did not only work on the GUI, but also implemented some new Features, which are listed below:
- SimPe is no longer using the Registry to store user Settings
- SimPe will now search for Updates when you start it. If you do not like that, you can disable that feature in Extra->Preferences…
- Includes a first Version of the Skin Workshop, which (at its current state) only allows you to clone a Skin (some fixes are already performed, but for example the 3IDR Files get not fixed yet)
- Fixed the GUID Scanner
- GUID Scanner will List the names of the package a GUID was first found in (for duplicates only)
- Type Descriptions are now generated from the Data/tgi.xml File
- Gmdc Plugin will now remember the Axis Settings
- Wallmasks should now be pulled correctly
- Reduced Maximum Number of allowed Vertices (Faces) to 2000 (5000). When not in AdvancedMode, SimPE will not let you import Meshes that have more Vertices/Faces!
- Fixed Problem with Neighborhood Backup and English Dates (as reported by TazzMann)
- Fixed flipping of the GMDC Preview
- NREF Resources are editable now
- The Raw View of the OBJd Wrapper now lists the Values in Categories (contains Updates by Numenor).
- Updated the Scan Folders Plugin. The corruption Scanner is now a Health Scanner and can check/fix OBJd Resources.
Packages can get reported as NonDefaultObjd, which means that you should resave them (You can use the Fix Package Button on the operations Tab to (batch)-fix those packages). In Advanced Mode, a package can also be reported as FaultyNamedObjd, which basically means, that the Filename that is written to the end of the OBJd is not the same as the one that was written to the beginning. This is technically not an error, and should not influence the game in any way, but you also can fix that by either recommiting the objd in question, or using the fix package Button. The last reported Problem is called FaultySizedObjd. This means that there are additional Bytes stored at the End of an OBJd. I found those in very old packages (had to restore a backup of my Downloads Folder to get these). - Added GUID, FileName and FileSize Fields to the Sim Browser
Finally one last warning. Thou the new GUI was tested nearly a Month in the QA, it is still very fresh.
If you do not like to use the new GUI, you can always install and execute the classic SimPE GUI, which is a part of the Setup File.