Recording analog from a turntagble or tape deck is not demanding of resources. Last year I copied 300 LP's to mp3 files. We were getting ready to move and I've been carrying those heavy LP's for years and rarely played them.
Your setup is quite adequate. The task is not demanding on pc resources. First thing is to get a pre-amp for the turntable, because the cartridge on a typical turntable doesn't put out enough signal for the normal audio in on a pc. Running it into the mike input is not a good idea. Over modulates easily. I got one for $9 from Radio shack. Battery operated. It's on or off. Just a little box the size of a pack of cigarettes. If you record from a tape deck, no problem, they have enought signal to just run into your line input.
Next is to pick out a good capture program. I still prefer Audiograbber. Yep, the same one that's been out for a number of years. You just pick Line input from the menu and away you go. Easy to control and yhou can add free encoders to give you whatever quality you want. As I say, very little demand on pc resources or cpu speed.
There are programs to clean pops and surface noise from LP's. I need to review the subject. I have such programs in my archives, but not my memory

I never found much need for the filters, but if your lp's are in rough shape it could be really useful.
You need more info just ask. I can review what's in my archives in the way of scratch and pop stuff.
What you are doing is not unusual, but great, because you can do most anything you want with the mp3 tracks after. Play 'em from the pc, make collections on cd's and play 'em on an mp3 player--which is what I do, connected to the regular stero setup.