Jeremy,
see this sticky thread for a review of external soundcards that we know work well with Audacity: https://forum.audacityteam.org/t/sound-card-reviews/8375/1 - I personally use the Edirol and find it produces excellent results. The iMic often gets a bad press on this forum - another regular poster on this forum (Kozikowski) has jettisoned his to his garage. - and mant folks seem to have problems getting them to work properly and cleanly.
I use an ART DJPREII phono preamp and am very pleased with this too (beautifully made, aluminium case): http://www.artproaudio.com/products.asp?type=90&cat=13&id=109
Another one that is recommended highly by another regluar poster (Kozikowski again) is this one: http://www.phonopreamps.com/tc750lcpp.html
Whatever pre-amp you buy - do ensure that you have a grounding post (to take the thin black earthing wire that should come out of whichever TT you have or buy). By and large I would prefer to do the RIAA equalization in good hardware rather than software - but if you are archiving 78s at all you may need to consider software equalization as there were many differnt curves employed by different manufacturers.
I would also consider the device that ART makes that integrates the phono preamp and the soundcard: http://www.artproaudio.com/products.asp?type=86&cat=9&id=128 - this device wasn’t on the market when I purchased otherwise I would have given it serious consideration.
I would no longer consider using one of the many available integrated USB turntables. In most cases they are cheaply made with platters that are far too light - you are likely to get wow&flutter (I certainly did with the ION ITTUSB that I started out with). I replaced the ION with the kit described above and rescued my old Technics deck from the attic, gave it a home service and treated it to a new cartridge. Just get yourself a good turntable and connect to a preamp/soundcard/Audacity.
Also buy yoursef a couple of external 1TB USB disks (quite cheap these days) to store the resulting WAV files that you will be creating. BUT don’t do recording direct to an external disk as it is unlikely to be able to keep up with digital audio capture.
With regard to Audacity the beta version is getting quite mature now - I use 1.3.8 all the time now. It has many feature extensions over 1.2.x - and we are likely to see 2.0 launched later this year hopefully - so you may as well learn the new interface straight away. IMHO it’s more stable than than 1.2.6 which is so old tha Noah probably used it before the Flood …
You may want to start out with a read of this article from the Audacity Wiki: http://wiki.audacityteam.org/index.php?title=Transferring_tapes_and_records_to_computer_or_CD
And this one: http://wiki.audacityteam.org/index.php?title=Splitting_recordings_into_separate_tracks
Have fun (I’m sure you’ll be back with more questions) - and welcome to the world of Audacity.
WC