What's new in MS-DOS 7.10 since MS-DOS 6.x?
There are many enhancements, new features and bugfixes in MS-DOS 7.10 since MS-DOS 6.x. For example:
* FAT32 and FAT32X drives support (*very* important nowadays)
* Extended FAT16 (a.k.a. FAT16X, type 0E, usually being the primary partition) drives support 
* Large hard disk and LBA ExtendedX (Int 13x) partition (type 0F) support
(*very* important nowadays) 
* Long File Names (LFN) support 
* Full Y2K (Year 2000) compliant and supports 4-digit years (e.g. DIR /4) 
* Large memory (>64MB) and XXMS 3.0 support 
* Euro sign support (Code Page 850, Right Alt+5) 
* The protection that keeps the stability of DOS 
* Efficient use of UMB memory (The DOS kernel and COMMAND.COM are loaded high  
automatically)
* Extended commands in CONFIG.SYS to use UMB memory, such as FILESHIGH,  
BUFFERSHIGH
* Environments variables can be used in the DOS command line directly, e.g. 
ECHO %PATH%
* The maximum length for path variable is expanded 
* Some new commands added, such as ACCDATE, LOGO(in CONFIG.SYS) 
* Volume LOCK/UNLOCK feature added to protect data and LFN on the (hard) disks 
* EDIT can be used to edit both text and binary files and multiple files 
* REN can rename a directory as well as files 
* The locations of DOS system files (especially IO.SYS) are much more  
flexible
* Dual-boot with older versions of MS-DOS (e.g. DOS 6.x)  feature added
* Animated startup logo support by using a custom LOGO.SYS file
* You can decide whether to execute a command using Enter/ESC key now while  
using the step-by-step feature 
* Support for loading Win9x GUI (including all versions from Win95/95A to
Win98SE GUI) on top added
* Many undocumented but useful options and switches added, such as COMMAND /Z 
* Updated and newer versions of DOS commands and tools included, such as MORE, MSCDEX, MSD 
* And many more...