My 20001 Vitara 2.) is over 260 000 kms now. I do notice a rattle when starting but I'm pretty sure it's the exhaust. 

But I was wondering if i should just change the timing chain anyways?  How much does it cost?  How much work is it?  If it were to break could i expect damage? 

About $300-600 if you do it yourself (plus any additional machine work or valve replacement costs over the basic cleaning and valve grinding) and probably in the range of $1200-$1400 if you have a garage do the same.

Why not try some Sea Foam in your oil for a few thousand miles to see if it quiets the noise first?  Sea Foam = $9 for a 16oz can at the local Dollar store.  I did this last Ocotober during an oil change.  I added about 2 ounces of Sea Foam during one change, about 1500-2000 miles later I noticed the distinct lack of the normal noise.  During the next oil change I added another 2 ounces to my oil.  

I had no control of what happened or didn't happen as far as maintenance to Buster before I bought him, but since I bought him, he gets regular maintenance.  No bullshit guys, after that 2nd oil change I haven't added anymore Sea Foam to my oil changes and my engine is totally "normal" sounding at start-up.  No rattles.  No noisy lifters.  Nada.  In fact, I went on a trip for a week and returned last week, left Buster sitting in the drive at home.  Came back, expected to hear some chain noise rattle at start up from the tensioners draining from having set for a week.  Cranked him and to my surprise.... NO noises.  Normal start up.  I'm sold on this stuff.

I'm NOT saying it repairs worn components that NEED replaced.  Nothing will.  I am saying it cleans the varnish build-up off of the internal components and allows them to function better... longer.

i got that rattle noise as well on both my 2002 vitaras,but only does it wen cold in the morning or parked for a long time, one is  at 216,000km and the other has 242,000km. now sumtimes it start to do it wile driving but only about wen i need to change the oil, i change it then its running fine, i expect both of them never had a regular oil change at the right km.

That's exactly what mine was doing before the Sea Foam treatment.  When it was cold... and when it had sat for a few days.  It doesn't do it anymore. 

I'm doing the Seafoam treatment to my 2003 2.0 Tracker right now. It started making the noise a little after it passed the 200,000 mile mark. The directions on the can say to add 1.5 oz's to 1 qt of oil capacity. Since my 2.0 takes 5.5 qts, I took that to mean 8 ozs. I didn't have the balls to put 8 ozs in, cause the stuff looks like water and gives an unsettling feeling when dumping it into the crankcase. I did put in around 6 ozs at the secong half of a 4,000 mile oil change. I still have the brief 1 second noise at startup, (but it's done that as long as I've owned it.) However, I'm not hearing the "chain slap" sound that caused my concern in the first place. I just addded a second 6 oz dose since I changed the oil 1500 miles ago. The engine is now at 206,000 miles and so far so good.

Be interesting to get yet another testimonial of how it did (or didn't) work for you.  Let us know.  Clean lifters, chains and tensioners work 'more better' without the varnish build up.

I may try this. Ill post results if I do.

Good.  The more feedback on results... the better.