Looks like i need to change my drive train on my winter beater. Chain is stretched and the rear cogs abit worn
front chainrings seem fine.

However questions is , if i am changing drive train and to ensure a new chain doesn't skip.

Is it in my best interest to just replace everything? including the front chainrings?
thanks
its an older mt bike. from 96.
thanks

Chain and cassettes are often replaced together, though it can be OK to replace only the chain if you do it in time. So if your chain is stretched LT 1/2% the odds favor you if you opt to replace only the chain. If the chain is stretched more than 1% the odds are against you, and reach near certainty if it's stretched much more than 1%.

Between 1/2% and 1% it's anybody's bet whether the new chain can run on the old cassette without skipping. I usually buy both, replace only the chain, and see how it runs. If the new chain runs fine on the cassette I save the new one for next time.

Chainrings are a different story. The chain wrap 180° and they're very tolerant of mismatched wear patterns. I'd estimate that most road riders can replace a number of chains and 3-4 cassettes before the chainrings are toast. But, of course it all depends on how long you let your worn chain go.

So, I'd say replace the chain and cassette (maybe) and see how it works before going for new chainrings.