I have InDesign but I use Quark. It's fine. I think a large part of the reason InDesign is so widely used is because it ships with CS (which designers will buy anyway) so the cost is comparatively tiny. That said, I think a number of people who have been in the game long enough to have an old copy siting around will be upgrading to Quark 9 for what looks like very well designed tablet publishing capability.
At 3 years I'm still very new to the industry, and as such have only ever used In-Design. Because like Dave has just said, it comes with the other Adobe products in the Creative Suite. It makes no sense to buy the CS then buy Quark on top.
That being said, I know some agencies that still use Quark, simply because they've been in the industry for so long it's what they know, and either don't have the time or have no need to learn a new program. Especially if they have deadlines to me.
thats the problem i am facing. when at uni and college it was all quark, and now for the last 6 years i work for a newspaper where its only quark as theyve used it for donkeys years and no need to change. However when i apply for jobs its all indesign hardly quark jobs. I try and teach my self indesign but cant get hold of a full working copy anywhere.
All i can say is keep trying i was a quark user for many years would not contemplate using anything else. As a printer i have to use other peoples created pdf files most of which are done in in design and quark does not like these when you are trying to run out plates but quark created pdf's work fine when used with in design so i had no choice but to get my head around it, now i rarely use quark just the odd business card but 90% of what i do is now in in design and it's great
I still use Quark, but then I learned Aldus Pagemaker before that.
It's the same with Illustrator, I used Aldus Freehand before that, but moved on due to my employer at the time requiring Illustrator-based work so that anyone in the team could edit it.
It's just about using whatever software technology is/was about when you're training or working professionally.
I also started in Pagemaker and Freehand, graduated to Quark and resisted Indesign for ages. I use Indesign all the time and only have Quark 8 as one client was using it also. Had problems with the pdfs made by Quark when running to plate - right pain in the neck!
If you can use one of them then learning the other will not be difficult.
I had Quark 4 and thought that I might like to upgrade to Quark 5, I didn't begrudge them some of my employers money. They said, 'there's no upgrade, you have to buy a new (£1000) version', I declined, I now use Indesign (cos it came with CS).