ok there is a way that took me a year of changing things around to get it to work.
but i have found an easy way to get dos games to work.
this works with both win vista and win 7
i am not sure if it maters with vista but with win 7 there are two ways to do it if u have 64bit or 32bit
32bit way.
open windows explorer.
copy and past link in address box.
C:\Windows\System32
then locate DPLAYX.DLL.
this is y u are having issues it because it was renamed from dplay.dll to dplayx.dll.
so once u find it u need to make a copy of it and past it in system32 ant rename it DPLAY.DLL.
so now u should have 2 of the same files but with different names.
it is a bit different with 64 bit.
paste link in address box.
C:\Windows\SysWOW64
then locate dplayx.dll
it may be easyer to search for the file it the search box once u r in C:\Windows\SysWOW64
then u do the same think as before but make sure u keep the file in the C:\Windows\SysWOW64 file as it wont work.
so copy and rename it and it should all be good with no need to download a dosbox.
hope this helps.
nick