gts 250 upgrade to what else??

hello ive got a alienware aurora 7500 the older model with a ASRock 960GC-GS FX mobo and a gts 250 gpu its geting kinda old and slow and i need to upgrade to something better that can handle my gaming needs i play world of tanks and infestation survivor stories please help me out, idk what my psu wattage is since the box is unmarked i have no way of checking what my psu puts out unles there is some type of software that can scan for it. guys here are my mobo specs===

Manufacturer ASRock

Model 960GC-GS FX (CPUSocket)
Version To Be Filled By O.E.M.
Chipset Vendor AMD
Chipset Model 780G
Chipset Revision 00
Southbridge Vendor AMD
Southbridge Model SB700
Southbridge Revision 00
System Temperature 38 °C
BIOS
Brand American Megatrends Inc.
Version P1.40
Date 10/2/2013
Voltage
CPU CORE 1.304 V
MEMORY CONTROLLER 1.832 V
AVCC 3.248 V
3VCC 3.232 V
VIN5 1.688 V
PCI Data
Slot PCI
Slot Type PCI
Slot Usage Available
Bus Width 32 bit
Slot Designation PCI1
Characteristics 3.3V, Shared, PME
Slot Number 0
Slot PCI
Slot Type PCI
Slot Usage Available
Bus Width 32 bit
Slot Designation PCI2
Characteristics 3.3V, Shared, PME
Slot Number 1
Slot PCI-E
Slot Type PCI-E
Slot Usage Available
Data lanes x1
Slot Designation PCIE1
Characteristics 3.3V, Shared, PME
Slot Number 2
Slot PCI-E
Slot Type PCI-E
Slot Usage In Use
Data lanes x16
Slot Designation PCIE2
Characteristics 3.3V, Shared, PME
Slot Number 3


Here is what my graphics looks like as far as specs===

Graphics
Monitor
Name Generic Non-PnP Monitor on NVIDIA GeForce GTS 250
Current Resolution 1280x960 pixels
Work Resolution 1280x932 pixels
State Enabled, Primary
Monitor Width 1280
Monitor Height 960
Monitor BPP 32 bits per pixel
Monitor Frequency 60 Hz
Device \\.\DISPLAY1\Monitor0
NVIDIA GeForce GTS 250
Manufacturer NVIDIA
Model GeForce GTS 250
GPU G92
Device ID 10DE-0615
Revision A3
Subvendor PNY (196E)
Current Performance Level Level 1
Current GPU Clock 300 MHz
Current Memory Clock 100 MHz
Current Shader Clock 600 MHz
Voltage 0.950 V
Technology 65 nm
Die Size 330 mm²
Transistors 754 M
Release Date Mar 3, 2009
DirectX Support 10.0
DirectX Shader Model 4.0
OpenGL Support 3.0
Bus Interface PCI Express x16
Temperature 39 °C
Driver version 9.18.13.4052
BIOS Version 62.92.7d.00.51
ROPs 16
Shaders 128 unified
Memory Type GDDR3
Memory 1024 MB
Bus Width 64x4 (256 bit)
Anti Aliasing Modes -?-
Filtering Modes Bilinear, Trilinear, 2x Anisotropic, 4x Anisotropic, 8x Anisotropic, 16x Anisotropic
Noise Level Moderate
Max Power Draw 150 Watts
Count of performance levels : 2
Level 1 - "Default"
GPU Clock 300 MHz
Memory Clock 100 MHz
Shader Clock 600 MHz
Level 2 - "3D Applications"
GPU Clock 738 MHz
Memory Clock 1100 MHz
Shader Clock 1836 MHz



PLEASe HELP!!!!!!!!!!!