You may need a couple different size Tungstens and will need a dedicated wheel or belt to sharpen them. Also some TIG nozzles (gas cup) and collets of the appropriate size for your torch and Tungsten size. It looks like one 3/32" collet and gas cup come with the unit. I'd consider an 80 C.F. Argon tank at least.
There's some info here and links to other resources:
http://www.millerwelds.com/resources...ints_tips.html
More info:
http://www.thefabricator.com/article...right-tungsten
I've had this seller (Tungsten-Direct) recommended for Tungstens:
http://shop.ebay.com/merchant/tungsten-direct
Were you going to get the 4043 filler rod? Have a size in mind?
Here's a link to the Miller manuals in case you want to read up. Page 31 has more info on the Tungstens and sharpening.
http://www.millerwelds.com/service/o...uals.php?model
Edit: If you want to weld Aluminum (and have 240v power available) another choice would be a Hobart Handler 210 with spoolgun. It's available in a package for under $900. To do both steel and Aluminum you'd need two gas cylinders - Argon and Argon/CO2 mix, but overall cost would be less. MIG is easier to learn than TIG.
http://www.northerntool.com/shop/too...2663_200392663