As is customary, to help others following along the path, here's some instructions for installing Linux (Kubuntu 11.04 but I'd guess any modern distro would be a similar experience) on a 2011 Dell E5420. In case the particular specification has an impact on the steps needed I've appended it to the bottom of this post.
These steps assume you have a prepared bootable install medium. I use a USB key, but CD/DVD would be similar.
Step 1 (optional): Ensure laptop is connected to mains and network (best to use wired).
Step 2: Press F12 during BIOS spash screen to reach boot menu, and select your boot media.
Step 3: When install option comes up, select it. Accept all defaults and complete user information as requested/desired.
Step 4: When instructed, reboot laptop. If using USB and an SSD this is in less than 5 minutes.
Step 5: Everything works. Enjoy :)
Sadly this traditional post is basically pointless, because it was that easy. All but one of my nieces could have done it (the youngest is only a month old, give her a chance...). In less time than it takes to install a Windows service pack you can take a blank laptop and transform it into complete working environment with all the core applications (office suite, etc.) already installed. No technical expertise required.
PS Rather nice, solidly built, nice to use laptop, in case you're interested. 3 mouse buttons on the Trackstick too. Battery lasted 7 hours out of the box, including all the install work :)
Spec (yes, no Microsoft Windows was supplied nor paid for):
Processor : One Intel Core i3-2310M (2.10GHz, 3MB cache, Dual Core)
Display : 14.0in UltraSharp HD+ (1600X900) AntiGlare LED-backlit with Premium Panel Guarantee
Palmrest : Dual Point Touchpad and Trackstick
Camera : Integrated Full HD Camera with Microphone
Memory : 2GB (1x2GB) 1333MHz DDR3 Dual Channel
Hard Drive : 128GB Mobility Solid State Drive
Optical Drive : DVD +/-RW Drive
Battery : Primary 9-cell 87W/HR, 3 Year Warranty
Wireless : Dell 375 Bluetooth Card
Wireless Card : EMEA Intel Centrino Advanced-N 6205 (802.11 a/b/g/n) Half Mini Card
Keyboard : Internal UK/Irish Qwerty Backlit Dual Pointing Keyboard (antimicrobial)
OS Media : Not Included