Upgrading dell Inspiron 545s graphics card

Since its a slim line case, the choices i have for a card are very limited. My PSU is also 250w. Id be willing to upgrade the psu as well, i just need to know the right type to upgrade too.

Time of this report: 2/4/2013, 18:24:55
Machine name: MATT
Operating System: Windows 7 Home Premium 64-bit (6.1, Build 7600) (7600.win7_gdr.120503-2030)
Language: English (Regional Setting: English)
System Manufacturer: Dell Inc.
System Model: Inspiron 545s
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: Intel(R) Core(TM)2 Duo CPU E7500 @ 2.93GHz (2 CPUs), ~2.9GHz
Memory: 6144MB RAM
Available OS Memory: 6134MB RAM
Page File: 2222MB used, 10042MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7600.16385 32bit Unicode