NUC Build:
NUC: Gigabyte BXBT 2807 (199)
RAM: Crucial DDR3 1333 SODIMM (4GB) (50)
SSD: PLEXTOR M6S 128GB (109)
OS: Windows 7 Home Premium (125)
Total cost: $483
Buy at Laser Distributer, #05-58. DIY yourself. If you can't into DIY, go to PC Care & Solutions, #02-32, SLS, and have Nigel assemble for you for a fee.
ATX build:
CPU+ Mobo: ASROCK H81M-HDS + G3240 (156)
RAM: G.SKILL PC 12800/1600MHZ DDR3 CL11 VALUE RAM (4GB) (50)
SSD: PLEXTOR M6S 128GB (99)
HDD: TOSHIBA 1TB 7200RPM (69)
DVD-RW: LG 24X DVD-RW SATA OEM (25)
PSU: FSP 300W 80% ATX PSU (39)
Case: CM K282 / K350 / K380 (55)
OS: WINDOWS 7 HOME PREM (125)
Total cost: $618
Buy at PC Themes, #04-15, and ask for discounts. DIY yourself. If you can't into DIY, get PC Themes to assemble for you for a fee.
Notes:
1) The Intel Celeron CPUs in these systems are more than enough for your needs.
2) The NUC can only hold 1X 2.5'' drive due to its very small size. If you wish to have more storage, can considering buying a 1TB external HDD for storage.
3) Got Mastercard? Consider buying the SSD from lazada.com on a Monday and get 10% discounts when you pay with a Mastercard.
4) If you are looking for Fortran, he is on a temporary break due to family matters.