They say a picture is worth a thousand words, so here's a 15 minutes mockup I did in photoshop:
1. Minor cosmetic changes
In Windows Vista/7, the default UI font is Segoe UI 9pt. Currently, some of the interface/config still uses Windows XP's Tahoma 8pt. Not a big deal, but I like my Segoe UI
2. Per drive settings
I would really like to be able to set some defrag defaults, and adjust them when needed for each one of my drives/partitions. Each one of my drives/partitions contains completely different kind of files and I would really like to be able to control how each one gets defragmented.
3. Moving files to the end of the drive based on date
Don't know if this should be separated from the file size (for example: any sized files with last accessed > 2 months ago), or used with the file size (for example: file is over 500 MB AND last accessed > 2 months ago), but I would really like for one of my partitions to be able to move all files > 100 MB with last modified > 6 months ago to the end of the drive. Available options should be Modified and Accessed (don't really see any use for Created) and the time period in Days, Weeks, Months & Years
Also, Schedule should probably be a global setting, right above About on the side menu instead of a per/drive setting like in my mockup.