My son asked me about watching The Transformers animated series. I looked it up on Wikipedia and it looks like there have been a lot of different reboots. Is the 1984 series where it all starts and how can I tell which version I have when I look at the DVD in the shop: I'm not sure how I'll know that I've got the right DVD or how to order it to ensure I get the right one?
There have indeed been several reboots. Even the original series contained two different versions: comics and television continuities. But to answer the question in the title: yes, the 1984 cartoon series (and the related comics) start at the beginning of the story. The first episode is set on their home planet, Cybertron.
However, I suspect he is referring to one of the recent reboots, Transformers: Animated.
Personal opinion: Transformers: Animated is geared more to today's youth. I suspect that, if you present him with the 1984 version, he will be disappointed. That is now mainly of interest to die hard fans (reliving their youth!).
Wikis has provided you with a completely correct answer, and I'm of the opinion that you should select it as the best one.
There is, however, something any price-conscious shopper should be aware of, should you choose to purchase the 1984 series DVDs for your son: there have been (at least) 2 different releases of the series on DVD. The first releases, between 2002 and 2004 have numerous problems.
Rhino's DVD boxsets have been criticized by owners. Various reasons include that the episodes as seen on the Rhino DVDs are based on incomplete 35 mm film masters, as opposed to the original 1" broadcast master videotapes aired on television. Although the film masters are very detailed and colorful, some of the episodes contain alternate or incomplete/missing animation that was originally corrected/completed for the broadcast versions. As a result, the DVD versions on some of the episodes are less "finished" than the versions that aired on television. Rhino attempted to fix some of the "new" errors, with lackluster results. Most of the errors are in the Season 1 box set with "Heavy Metal War" being the worst episode in terms of incomplete animation and bad attempts by Rhino to fix the errors.
In addition, the telecine transfer of the film masters turned out to be sub-par, and did not provide any proper 3:2 pulldown system for transferring the 24 frames-per-second film to 60 fields-per-second video. As a result, aliasing (jaggies) appear frequently in most, if not all, of the episodes.
Further, the Rhino versions of the episodes have a plethora of newly-added sound effects from a stock sound effects library (which many fans have said are annoying and distracting), sound effects that did not appear in the episodes as originally produced and broadcast. These sound effects were intended to only appear on the episodes' 5.1 soundtrack, but for select episodes in the Season 1 and Season 2 Part 1 sets, the stereo soundtrack also exhibited the added sounds. For the Season 2 Part 2 set, every single episode's 2.0 stereo soundtrack had the added sounds from the 5.1 track. It wasn't until the Transformers Season 3, Part 1 boxset that Rhino bowed to the fanbase and added an "original broadcast audio" option. These new sound effects were also applied to several European releases of the Transformers series, as well as to The Transformers: The Movie: Reconstructed DVD (although it should be noted that Rhino's own version of TF:TM does not have the added sound effects). Only serving to enhance the discontent, the sound studio responsible for this, Magno Sound, claim that the sounds were always there. (from the wiki article)
By all reports, the more recent releases (25th Anniversary Edition or "Matrix Of Leadership" Edition) do NOT have these issues.
Buyer beware - if you accidentally get the Rhino sets, the show will suffer for it.