ive done a lot of research on the mother board you chose, its a really good board, you wouldnt have any problems with it...
PLEASE PLEASE PLEASE *DO NOT* get the Antec 300 Case... its absolute garbage... here are MUCH better cases for less or the same price...
MY current Favorite case, has good cable management, can house up to 7 fans, black interior, USB 3.0 front I/O mother board header and you can get it black or white, it is a clean minimalsitic and performance oriented case:
NZXT Source 210
Newegg.com - NZXT Source 210 S210-001 Black “Aluminum Brush / Plastic” ATX Mid Tower Computer Case
my old favorite case before the Source came out is the
Newegg.com - NZXT GAMMA Classic Series GAMA-001BK Black Steel ATX Mid Tower Computer Case
this is baisically a NZXT Gamma with a side window,
Newegg.com - NZXT M59 - 001BK Black Steel ATX Mid Tower Computer Case
Anyone of those cases wil destroy the Antec 300...
also, the i5 2500k processors love being overclocked so much, it would be foolish not to overclock it, especially with how EASY it is to over clock them nowadays. so defiantly get a CPU Cooler, you can get a good 30%-40% more performance out of your processor. this is the all time best bang for your buck CPU cooler, with this cooler you can reach 4.4-4.5ghz with ease
Cooler Master Hyper 212+
Newegg.com - COOLER MASTER Hyper 212 Plus RR-B10-212P-G1 "Heatpipe Direct Contact" Long Life Sleeve 120mm CPU Cooler Compatible Intel Core i5 & Intel Core i7