You can only take 5 albums to a deserted Island...

But there is a world class system there for your use.  Leaving many favorites behind but I must have:

Yes - Close to the Edge
Rolling Stones - Beggars Banquet
Robin Trower - Bridge of Sighs
Neil Young - Everybody Knows this is Nowhere
John Lee Hooker - Mr. Lucky

Deep Purple - Machine Head
Led Zeppelin - II
Dire Straits - Brother in Arms
ZAZ - Recto Verso
Pink Floyd - The Division Bell
Once we all get to the Desert Island, this island will be nicely stuffed with music!!!    :-)
DANVIGNAU, thank you for flushing PF fans out of the closet, because I was a bit worried what is happening here. So, while we all On The Island, here is the list of my 5 Must-Haves which I see missing from the collection:
1) Tchaikovsky's 5th under Mravinsky
2) Bruckner's 8th under Celibidache
3) Dead Can Dance box set
4) Cocteau Twins box set
5) Klaus Schulze Mini-LP CD box set
Some other painful (for me) omissions on this thread here are:
6) Porcupine Tree
7) quite a few must have or "We Must Die" from ECM label, starting with "Khmer".  Those who ever loved Miles must give it a listen!
8) Tubular Bells (!!!)

Here are my 5 in no particular order:

1) Beatles - Rubber Soul

2) Beatles - White Album

3) Rolling Stones - Beggar's Banquet

4) U2 - Joshua Tree

5) Derek & the Dominos - Layla

First substitute (#5b): Dylan - Highway 61 Revisited

Gotta have some variation for my 5:

1)  Pink Floyd - Dark Side of the Moon
2)  Norah Jones - Wish You Were Here
3)  Miles David - Kind of Blue
4)  Bach's Cello Suites - Janos Starker 
5)  AC/DC - Back in Black

Ginger and Mary Ann would improve this whole hypothetical scenario thing, as well!
If I was forced to grab 5 it wouldn't be something I know. I have those feelings and memories implanted. I think it would be some classical music I've only dip my toe into  and hope I chose wisely and I don't hate it. But just in case Id try and snatch a diamond of a Jerry Garcia Band show, and pray it wasn't a snoozy noodle fest.  He always played great covers of all kinds of essential stuff snd covered the gamut from ballads, jams from heaven, reggae, bluegrass, timeless Hunter-Garcia collaborations. Honestly though a desert island would be music enough, sweet sounds. If I was given a choice between music or a surfboard though that would be tough, but with push come to shove, no contest. I'd leave the classical and grab my 7'2 Pendoflex.