Windows 7 Some Resolutions Not Availble

I have a 19" monitor that is 1440x900. When I turned my computer on it was set to 1024x768. It looks all distorted and stretched. Very disgusting. My computer has no option for 1440x900. Only 800x600 and 1024x768. Please help me! I checked all the settings and restarted my PC.
Here's the specs:

Processor

• Type Intel Pentium Dual Core E2220 / 2.4 GHz
• 32-bit processor Yes
• Installed Qty 1
• Max processors supported 1

Mainboard

• Chipset type NVIDIA GeForce 7100
• Data bus speed 800 MHz

RAM

• Installed Size 4 GB / 4 GB (max)
• Technology DDR2 SDRAM
• RAM form factor DIMM 240-pin
• RAM configuration features 2 x 2 GB

Storage

• Hard Drive 1 x 640 GB - Standard - Serial ATA-300

Monitor

• Acer X193w

Graphics Controller

• Type Plug-in card
• Graphics Processor / Vendor NVIDIA GeForce G100
• Digital Video Standard Digital Visual Interface (DVI) , High-Definition Multimedia Interface (HDMI)

Networking

• Networking Network adapter - Integrated
• Wireless LAN Supported Yes
• Data Link Protocol Ethernet , IEEE 802.11b , IEEE 802.11g , Fast Ethernet , Gigabit Ethernet , IEEE 802.11n (draft)
• Compliant Standards IEEE 802.11b , IEEE 802.11g , IEEE 802.11n (draft)

Expansion / Connectivity

• Expansion Bays Total (Free) 1 ( 0 ) x Internal - 3.5" x 1/3H , 1 ( 0 ) x Front accessible - 5.25" x 1/2H
• Expansion Slots Total (Free) 1 ( 0 ) x Processor - LGA775 Socket , 2 ( 0 ) x Memory - DIMM 240-pin , 1 PCI Express x1 , 1 ( 0 ) x PCI Express x16

Operating System / Software

• OS Windows7 32 Bit
• Software eSobi (OEM) , Acer Arcade Live , Microsoft Works 8.5 , Adobe Acrobat Reader , NTI Media Maker (OEM) , Acer Empowering Technology , McAfee Internet Security Suite (Trial) , Microsoft Office 2007 Home and Student Edition (60 days trial)

Thanks in advance!