Building 24/7 Small Business/Home Server

Planning to build a 24/7 small business/home server for downloading, Media storage/sharing . please suggest me good rig for this purpose.

I want :
1.motherboard
2.processor
3.ram
4.2TB hdd
5.SMPS

BUDGET - 15k +/-

I already have:
Antec Sonata-II Cabinet
keyboard + mouse
DVD drive
Monitor

Planning to use windows home server V2 or windows server 2008 with this rig..

Plz suggest me a efficient, future proof rig for this purpose.

Thanks in advance

Regards,
Navin