Do not trust checking your Windows 95 version by typing VER at a DOS prompt. Win95a will report itelf as 4.00.950 erroneously at the DOS prompt. The correct way to check your Windows 95 version is as follows:
Go to Start/Settings/Control Panel/System/General tab. On that tab there is "System:" It will show the correct Windows 95 version number. The version numbers are a follows:
4.00.950 is original release Windows 95 aka Windows 95 "Classic."
4.00.950a (aka "Win95a" or "OSR1") is the above with "Service Pack 1" applied or included.
4.00.950b or 4.00.11111 is "OEM Service Release 2.0" ("OSR2" aka "Win95b")
4.00.950B or 4.03.1212-1214 is "OSR2.1": Basically "OSR2" plus the Universal Serial Bus (USB) update
4.00.950c or 4.03.1214 is "OSR2.5": which is basically OSR2.1 above plus IE4.01 and other addons.
4.01.0970a or 4.01.0970b See the Windows 95 Version Notes from Windows Magazine about this one. Basically, an addon called "MSAA" changes/updates the USER.EXE file in Windows.
4.10.1602 or 4.10.1650, etc. are outdated Windows 98 Beta releases!!
4.10.1998 is the final release version of Windows 98
4.90.xxxx is a Beta Windows Millenium or "ME" (xxxx is the build number) Example: 4.90.2535
?.??.???? is Windows 2000
Windows Updates/Fixes: By all means check out this Windows 95 Updates page for all major and minor updates to all versions of Windows 95 itself. As of the 06/98 there are no official "Service Packs" for "OSR2.x" but there are some minor file and program updates. One addon to "OSR2" that comes on one disk only adds the drivers for the "Universal Serial Bus" (USB). There are also some other very useful user created fixes and patches that you should check out at the OSR2 FAQ pages.