You talking about this one: Marlin Model XT-22
I have no personal experience with this, but it looks like a really nice entry-grade rifle.
It looks like a nice set of features and if you like the way it handles and are ok with the trigger, then the only thing to do is to find someone who can vouch for the accuracy. Marlin's are historically decent to great shooters and I'd be surprised if this isn't even better than the "oldies". I have a Marlin 15-YN that my kid sister loves to shoot...it's quite an accurate gun with the same Micro-groove rifling as the XT-22 barrels. I would imagine you will be very happy with that Marlin...esp for the prices I'm seeing
Tracked down a review on the rifle, but again, you need to find someone you trust to give you some feedback on the rifle's general accuracy capabilities.
The FAL Files Forums - Marlin XT22 Review - Out of the Box
Regardless of what rifle you buy, just "bite the bullet" and buy a box of as many difference ammo types as you can find and test them all through your gun before you settle on one for each application. As I mentioned, I have three different loads that I run through my gun; one each for hunting, competition/fine accuracy and one for practice/plinking. Rimfires -and especially .22's- are very individualistic; what shoots well in my rifle (even of the same make and model) may not shoot well from yours. I recommend that you play with the cheap stuff first and settle on the one that shoots best from your rifle. If your accuracy expectations are met, then you're done! But if you need more accuracy for certain applications, then keep the cheap stuff, but also experiment with some higher dollar "match" or "target" grade stuff in the $6-$10/50 rounds range and find the one that shoots best from your rifle. I recommend starting with CCI "blue box", Winchester T22's, and Wolf MT's or Wolf MT Extra's.
Best of luck and let us know how it shoots!