A video card length of 9 inches is not too bad when compared to other cards. Some of them have a length of 11 inches. A 9 inch long video card is about the same as the width of a standard atx motherboard. The card will fit in just about any case that can accomodate a standard atx motherboard. A mid-tower or full tower atx case will be okay. Here is a link to an example of a mid-tower atx case that is very popular with gamers:
The general rule of thumb is a high quality 500 to 550 watt power supply with sufficient current (amps) on the +12 volt rail(s) can easily power a system with any single video card made. A high quality 700 to 750 watt power supply with sufficient current (amps) on the +12 volt rail(s) can power a system with two video cards operating in dual mode. There are a few exceptions like the new ATI Radeon HD 5XXX series cards which use less power due to their energy efficiency.
A high quality 500 to 550 watt psu will have a +12 volt rail rated at 40 amps. A high quality 700 to 750 watt psu will have a +12 volt rail rated at 60 amps.
In addition the power supply should be at least 80+ Bronze certified for energy efficiency. There are some models available which have achieved 80+ Silver and 80+ Gold Certifications.
Before purchasing a new psu you will need to decide whether you will eventually have a pc with one or two video cards.
Corsair and Seasonic are two of the brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Some of the newer models come with a 7 year warranty. Lately we've been seeing a few other brands offering some high quality units. One example would be the Antec Earthwatts series which is a major improvement over Antec’s older psu’s like the Basiq models.
If you want to go a little higher end for example to save you $$ on your next build:
Dragonlord K62 by LANCOOL (Lian Li company). Has some really sweet features, and totally worth the $99.99+ Shipping, you can do some research to find better prices, mwave.com I heard had good prices on them by Johnnylucky I believe.. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
For power supply: A good quality 450w power supply will be more then enough. However looking at prices you can get a 500w modular for the same price as a good quality 450.
OCZ 500w ModXstream for $64.99+$5.99 shipping. It's modular so it's great for cable management, and it's got solid performance. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
smps - 500W
processor - Pentium D
RAM - 3 GB DDR2
M board - D946Gzis
Hard disk - 500GB Seagate
OS - windows 7 X64 ultimate