I'm not sure if any cases have a built-in temperature monitor; you usually have to buy an aftermakret one. Most computer cases don't go over $300, but there are some...like the Thermaltake Level 10 with a heavy price of $800..
The Cooler Master Storm Sniper has a chassis fan control feature. Costs around $160.http://www.newegg.com/Product/Product.a ... -_-Product
Antec Dark-Fleet 85 ATX full-tower. Great airflow case. It has built-in fan speed control for ALL 7 the fans, but again, no temperature monitor. http://www.newegg.com/Product/Product.a ... -_-Product
Antec Lanboy Air ATX Full tower. This case really stnads out from the rest; you can basically build your own case! Moveable panels. Again you can control all the fans' speed individually. (Many of Antec's cases have this feature).http://www.newegg.com/Product/ProductLi ... lanboy+air
Thermaltake Element G ATX Mid-Tower Case. Just like the Storm scout, you can adjust the fan speed with one knob.http://www.newegg.com/Product/Product.a ... 6811133086
Thermaltake Element V ATX Full-tower. Fan speed & fan colour control. http://www.newegg.com/Product/Product.a ... -_-Product
You can always just buy a case without and fan control, and ADD your own control+monitor like these:http://www.newegg.com/Product/Product.a ... 6811992005http://www.newegg.com/Product/Product.a ... 6811999174http://www.newegg.com/Product/Product.a ... 6811998038
For the motherboard, I'd suggst that you go with one by ASUS, Gigabyte, or MSi. Recently, AsRock seems to be been doing a good job. If you are thinking of running a setup with 2 or more graphics cards, then get a motherboard with two or more PCI-E X16 slots (getting a board that provides X16 or X8 through the PCI-E slots are recommended, as X4 doesn't provide enought bandwidth for more powerful cards.)
Most ATX full-towers and ATX mid-towers will fit ATX sized motherboards (with 2 PCI-Ex16 slots or more), so you don't need to worry. Of course, if you get a motherboard that has like 6+ PCI-E X16 slots, they become E-ATX or LG-ATX and you need a specific case that supports them.
As far as power supply...for a Crossfire or SLI set up, a 650W or 750W a reliable, stable,quality brand like Antec, Corsair, XFX, Seasonic, SilverStone, or OCZ is ideal. For a single card setup, a 500W-550W should be plenty. Running three cards or more will require a a better power supply.
For RAM, DDR3 1333MHz or 1600MHz is suitable. There isn't a lot of noticeable performance between the two, but if you plan to do some pretty big overclocking, get 1600 RAM. I don't recommend that you get 1066MHz or slower RAM, as there are noitceable performance differences.