Good choices on everything except the power supply. To get your true (or more accurate) requirements, we must consult the oracle:
System Type: 1 physical CPU
Motherboard: Regular - Desktop
CPU Socket: Socket LGA 1155
CPU: Intel Core i5-2500K 3300 MHz Sandy Bridge
CPU Utilization (TDP): 90% TDP
RAM: 2 Sticks DDR3 SDRAM
Video Card 1: AMD Radeon HD 7850
ATTENTION: FOR PERSONAL, NON-COMMERCIAL USE ONLY
Regular SATA: 1 HDD
DVD-RW/DVD+RW Drive: 1 Drive
Fans
Regular: 1 Fan 80mm; 1 Fan 92mm; 2 Fans 120mm;
Keyboard and mouse: Yes
System Load: 90 %
Minimum PSU Wattage: 267 Watts
Recommended Wattage: 317 Watts
It's amazing what Ivy & Radeon 7x series can do for your power bill
The 7850 is a great price / performance deal, Nvidia's equal would be the 560ti-448 maybe better performance when OC'd but the power requirement would be higher. Good choice on the board, the Biostar-T's is great performance/quality at that price. Can't really comment on the monitor, aside from other Hanns LED brands at my local microcenter I think they look great and have good reviews so I would probably get one (I currently have an Acer 24"). The Lan-Li, yes the 212 will fit (according to other forum's users and a google search, I tend to use the Cooler Master Elite series, 212 will fit and usually can be had for under $50 shipped).
For your PSU, with the current system you have a 500+ unit would make a great choice and last for years - looking at newegg.ca's current crop of deals...
Rosewill Green Series RG530-S12 530W $55 + $4 shipping
Antec BP550 Plus 550W $60 + $6 shipped
I am sure that raidmax is "so-so" (a mediocre Andyson OEM) but I have heard of that brand / series just flat out going dead after a short time or gotten DOA so I would probably stay away.
If you want the higher watts, then this would be a good pick
Rosewill Green Series RG630-S12 630W $65 + $4 shipping
If you are not sold on rosewill, check out the
Hardware Secrets review they gave it really good marks (what sold me on the Rosewill RG series)
cheers