Hello, Both files are the same, but with a different install package. One as you know is for installing while running Windows. The other is installed with the system is booted to DOS. Since you successfully installed the Windows file, you do not need to install the other.
Inspiron 530 Dell Vista 32 Bit.....This is a new firmware update on the Dell downloads site.  It has two .EXE files one for windows and the other a dos file.  Both are supposed to be run as far as I can tell. The windows loaded perfectly but the dos kept coming up with a message that the system does not support full screen mode.  So that file would not load further.  Dell does not give very much detail in their download section so I don't know if I have a problem or not.  Has anyone tried this download?  It came out 12/23/2009.  Thanks.
DELL FIRMWARE UPDATE DVD CDRW