Mini ITX build( first post )

Hello this is my first post on toms hardware ever

I am planning on building a mini ITX to replace my p4 internet browsing pc, I have already decided on most of the parts however I am unsure if these part will run well on a 120w psu which comes with the case

here is the build so far

CPU: Intel Pentium g850 1155

mother board: Asus P8H61-I B3 micro ITX

Ram: Hynix DDR3 PC10660/1333MHz 4GB

case + PSU: In-Win BM639 120W

hard drive: 320gb 2.5 SATA 5400rpm (have yet to decide between wd or seagate), no optical drives

I am considering getting it a low profile video card in the 6570 range in the future, probably waiting for AMD HD7570 (hopefully the southern islands 28nm die shrink will help with power consumption) but I am unsure if the small power supply will be able to comfortably handle it, Ive seen reviews of the Pentium that have a whole system without video card running at about 80w in total but am still unsure if a low end video card would be to much or not.

I will be using this for internet browsing, very light gaming if a video card is an option and just general productivity eg word.

If you wold like to recommend better parts please acknowledge that I live in New Zealand and prices are out of proportion so check on pricespy(http://pricespy.co.nz/) before recommending and also that price and size are a high priority in this build.

all help is appreciated, thanks