From a not too distant location, this is probably the most
convenient way to approach Zürich. There are frequent connections in
all directions, from Germany by ICE, from France by TGV, and from
Italy by Cisalpino. Some approximate travel times: Basel (1h),
Karlsruhe(3h), Milano (4h), Frankfurt (4h), München (5h), Paris
(6h), Amsterdam (8h), Berlin (8h), Roma (8h), Wien (9h), Praha
Zürich's main station is referred to as Zürich HB. It is located in walking distance (10-15 minutes uphill) to ETH. More details regarding train connections can be inquired from the Swiss Railway Website or the German Railway Website.
Zürich airport has its own
railway station called Zürich Flughafen. The trip from
Zürich Flughafen to Zürich HB takes about 10 minutes. During peak
times, there are 10 connections per hour, between 11pm and midnight
there are still four, but between 0:10 AM and 5:00AM there is
The route is part of ZVV, the public transport network of Zürich, zones 10 and 21. The tickets are valid for all public transport within these zones, let it be train, tram, bus, or boat. In particular, as Zone 10 includes the city of Zürich, these tickets are also valid for tram or Polybahn that take you from Zürich Central to ETH.
Valid here means that you can make as many trips as you like within the given timespan. If you do not want to go back to the airport within the next 24 hours, a single fare ticket should be your choice. (You can buy a one day pass for CHF 7.60 that is valid for Zone 10 (Zürich city) only when you do your next tram trip in Zürich.)
A taxi from Zurich Airport to the city should cost about CHF 50-60 (€30-40). Ask the driver to bring you to ETH Zentrum/CAB, Universitätsstrasse 6.
Zürich can easily be reached by car as well, travel times are similar as given above for train. See any standard routeplanner for details; a good online map for Switzerland can be found here. There is a speed-limit of 50km/h within towns, 80km/h outside tows, and 120km/h on motorways. In order to use motorways, you need to buy a vignette that costs CHF 40 (~ €25) and is valid for one year. The vignette can be bought at any border crossing or gas station, rental cars usually come with it.
This is not really fun, in particular, if you do not know exactly where to go. There are lots of one-ways and areas that are not accessible to private cars. Most importantly, there is no place where you can park your car free of charge. Most parking lots are within a so-called blue-zone, for which you need a parking-ticket (Tagesbewilligung Blaue Zone) for each working day incl. Saturdays. Such a ticket costs CHF 15 (~ €10) per day; it can be obtained online from Stadtpolizei (pages in German only).