Inspiron 530s help?

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System Information
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Time of this report: 10/2/2010, 19:50:39
Operating System: Windows Vista™ Home Premium (6.0, Build 6000)
System Manufacturer: Dell Inc.
System Model: Inspiron 530s
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: Intel(R) Pentium(R) Dual CPU E2200 @ 2.20GHz (2 CPUs), ~2.2GHz
Memory: 3036MB RAM
Page File: 1812MB used, 2479MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 10
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Display Devices
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Card name: Intel(R) G33/G31 Express Chipset Family
Manufacturer: Intel Corporation
Chip type: Intel(R) GMA 3100
DAC type: Internal
Device Key: Enum\PCI\VEN_8086&DEV_29C2&SUBSYS_020D1028&REV_02
Display Memory: 286 MB
Dedicated Memory: 0 MB
Shared Memory: 286 MB
Current Mode: 1440 x 900 (32 bit) (75Hz)
Monitor: Generic PnP Monitor
Driver Name: igdumdx32.dll
Driver Version: 7.15.0010.1472 (English)
DDI Version: 9Ex
Driver Attributes: Final Retail
Driver Date/Size: 4/18/2008 18:12:18, 552960 bytes
WHQL Logo'd: Yes



OKAY thats my comp. um im trying to fit a Palit NE5S4500F0601 GeForce GTS 450 (Fermi) 1GB 128-bit GDDR5 PCI Express 2.0 x16 HDCP Ready Low Profile Ready Video Card



but apparently my comp isnt good enough (so the best buy guy said.) he recommended that i would need a better power supply because most 530s models come with 250w and finding a power supply to fit into the comp will cost a lot. so my question is, will it be cheaper to just buy a new decent gaming computer or to upgrade this 530s model? 'cause i can always return the graphics card.

EDIT: i have the slim tower 530s. so the power supply and graphics card space is very very limited.