Hmm... about 15. First time I extensively tinkered and used Linux was at 16 though, with Ubuntu 8.04.

I started out with Pre-Novel SUSE when i was 15 and now i am 22. My first under taking as a Linux Virgin was to configure a Samba/Cup file and print for the family network. For that project i used SUSE because it was affordable and well documented. At seventeen my father purchased a custom gaming PC from a local PC builder/repair shop near are then home town of Tenafly NJ, after about fifty reinstall of Windows I distribution hopped on that rig before I settled temporally on Ubuntu. The once i landed a part time job in high school I saved up my pay checks and purchase a Mad Tux Custom built fedora core 4 rig whi open receiving i tried every thing from Ubuntu to Debian and settled on Debian 4.0. The my mother got a new desktop for Christmas 2006 and i acquired her old Dell and turned it into yet another Family Samba File server which hosted a centralized iTunes library. The summer my sister went off to college i acquired her old dell Dimension 4600c and turned it into a pseudo Linux entertainment center using Ubuntu8.04 Hardy Heron.

Following is a list of every Ubuntu release i have ever used

Dapper Drake.6.10 LTS

Feisty Fawn 7.04

Hardy Heron 8.04 LTS

Ubuntu 9.10 (Karmic Koala)
Lucid Lynx 10.04

xubuntu10.10 Maverick Meerkat

I have used the following Debian releases

Woody
Etch
Lenny
Squeeze
Sid

Currently I am running RHEL Client Side 5.5 on surplus desktop given to me by my fathers company.
MY current laptop runs the latest Long Term Support Release of Ubuntu. 10.04 (Lucid Lynx).

2001, I was aged 24 and installed Suse Linux 7.3.

19 I think - a version of Slackware that came on a cover of PC Quest. I didn't have video drivers for my card, and it didn't work, that is to say, get graphical/GUI for months until I got hold of the next version.