$60? Yeah that might bw worth it then. As for the case, well, it'll be warm. If the card has the blower style cooler like the one you linked then it should be ok because it exhausts outside the case. Just make sure it'll physically fit.
The card should fit if there is no hard disk drive in the second internal HDD bay.
For a system using a single Radeon HD 4890 graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 30 Amps or greater and have at least two 6-pin PCI Express supplementary power connectors.
The XFX Core Edition PRO550W (P1-550S-XXB9), with its +12 Volt continuous current rating of 44 Amps and with one 6-pin and one 8-pin PCI Express supplementary power connectors, will more than meet the requirements.