http://www.oldfiles.org.uk/powerload/index.htm  For CD and DOS drivers plus loads of helpful advice.

http://groups.msn.com/win3x  Might seem ironic for Microsoft to host support groups for an OS that they have long since ceased to support but it has to be remembered that it is still a Microsoft product.

www.mwpms.uklinux.net An absolute must. Highly recommended site. 
Loads of info about DOS with many downloads. Especially impressed with a DOS GUI called DOSSTART which looks very much like Windows 95.

www.computer5.com  Another impressive site.
A comprehensive computer web directory.

www.calmira.de To give Windows 3.1 the Windows 95 look.

www.qbasic.com Excellent QBASIC resource.

www.oldos.org/os.htm 
Support for every flavour of MS and IBM DOS from version 3.2 upwards, MicroSoft  Windows (versions 1.01 to 3.11) and IBM OS/2. (Content seems to change radically from time to time).

Also.........

Some Windows 95/98/ME Stuff

www.grisoft.com         AVG Anti-virus software. Free with free updates.

www.zonelabs.com   Free Firewall software. Also to be found on many CD cover disks.

Will prevent unauthorized access to your computer.

www.winzip.com         WinZip is a Compression Utility which can be downloaded for a free 30 days trial (After this you will be invited to either pay for it or stop using it). It makes files smaller so that they are faster to upload and download. More importantly once installed (Just double-click once it has been downloaded) it will decompress any zip simply by double-clicking on the file. (Not needed if you are running Windows ME or Windows XP.)