Capt Wafoo
What Mac is it???? 25MHz - an LC475??
They are more than capable of running e-mail and internet, although an older browser such as Netscape 2.1 would be best.
Serial modems still available, around £90 ex vat.
Problem is with system software. Ideally upgrade it to 7.6.1 which has all bits necessary. Is possible to run on older systems - ie7.1 or later, but will require bit of shareware like FreePPP, and MacTCP.
regards