Please re-read Ziggy's answer below. I agree with it. It seems to me that you are conflating "not believing in Santa" with "not havng a festive holiday." As she said -- what does Santa belief by young kids have to do with baking, shopping, lights, etc.? You can do all those things and more, and your husband can be as agnostic about the religious roots of the holiday as he likes. I have friends who are agnostics (some single adults, some singles with kids, some married with kids) and all are VERY into their trees, ornaments, decorating, planning holiday meals, traveling or hosting, buying and wrapping, going out to see lights or even to festivals where there will be...gasp...Santas. Or even, dare I say it, accompanying family members to their churches, like my close friend who always goes to Christmas Eve service with her sister though my friend is agnostic. She can be agnostic yet still recognize that others whom she loves are celebrating a religious festival, and she can still appreciate the beauty of that celebration.
Don't confuse the idea of your kids not believing in Santa with totally tossing out all the other trappings and fun....Unless your husband is also against the other aspects of the holiday. Does he want to stop giving gifts altogether? Does he tell you not to decorate, or to stop baking stuff that is holiday-themed? If so, he has bigger issues here and YOU need to assert that you too have a right to celebrate a holiday that is meaningful to you, whether that meaning is religious or not. I'm guessing based on the post that he doesn't forbid things but just doesn't join in your happiness, either, right? That's sad, frankly.
As for your boys and how they "don't seem to notice or value" making memories -- two things. One, they are at ages when they are wrapped up in themselves, as kids these age quite normally are, and mostly should be; so relax and remember that a lot of what you do IS soaking in and if you dropped the traditions suddenly -- I bet they'd let you know they really WERE paying attention and liked what you all do. And second: Make sure that those memory-making traditions are what you ALL do and that Christmas isn't just about mom, but that you have the boys doing things too -- especially doing something like filling stockings for a charity, helping with a Toys for Tots Drive, baking cookies and then going a step further and taking plates of those cookies to the firefighters at the fire station or the folks at the nursing home....Ensure that they help decorate, they help bake, they get out and tour the lights with you, and they do something for other people at this time of year. Those things aren't agnostic, atheist or Christian, they're simply fun and helpful, and if your husband somehow objects, you and he need to talk big-time.
As for the immediate question of the Dec. 25 gifts: Let them just appear overnight under the tree marked for the boys and don't mention Santa at all. The boys know they're from you. I would be very interested to hear if at least one of them pipes up, half-jokingly, "Hey, are these from Santa?" Just give a sly smile and say, "Whoever they're from, they're FOR you!"
It also sounds a bit like you are mourning the passing of the days when your sons were more into getting lots and lots of gifts. I would just get them the few things you know they want, plus a stocking for each with a lot of small, fun items they can enjoy and it's not a big deal when those items lose interest for them. Take the time you would spend on buying lots of extra gifts and spend it on DOING things with them while they are off school.