Upgrade my PC into a gaming PC

[riahim]

I was wondering whether I can just upgrade my system into a gaming PC that can play most new games on high or medium settings. I realized I had some good components in my system, so I don't fell like spending over $1000 to build a new one.
I know I will have to replace the power supply and video card. Will this be enough or do I need other new components as well? My budget for upgrading is $300-400. Preferably towards the low end if possible.
Hopefully I can just upgrade my system and not have to build a new one? What do you think? What parts would you recommend for me? Also, If I upgrade, will the system still be upgradable in the future?

My specs are as follows:

Operating System
MS Windows 7 Ultimate 64-bit SP1

CPU
AMD Phenom X4 9550
Agena 65nm Technology

RAM
6.00 GB Dual-Channel DDR2 @ 401MHz (6-6-6-18)
Motherboard
ECS Nettle3 (Socket AM2 )

Graphics
HP w2408 (1920x1200@59Hz)
256MB GeForce 9300 GE (Unknown)

Hard Drives
733GB Seagate ST375063 0AS SCSI Disk Device (RAID)

Optical Drives
DTSOFT Virtual CdRom Device
TSSTcorp CDDVDW TS-H653Q SCSI CdRom Device
TigerJet CD-ROM USB Device

Audio
Realtek High Definition Audio

See this link for more info: http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&taskId=120&prodSeriesId=3733093&prodTypeId=12454&objectID=c01498952

EDIT: Forgot to mention I have a 24in screen with 1920x1200 Resolution.

Thank You in advance

 

[xsamdagreatx]

first of all you need to specify what kind of psu do you have and the voltage. from the looks of this hp i would that gpu needs an upgrade(based on the psu) , and you should add a SATA II SSD in there as your primary harddrive. your ram is fine for now but just an advice you should start saving money to build a new rig in a year or so because even with the upgrades this computer wont last very long.

 

[riahim]

first of all you need to specify what kind of psu do you have and the voltage. from the looks of this hp i would that gpu needs an upgrade(based on the psu) , and you should add a SATA II SSD in there as your primary harddrive. your ram is fine for now but just an advice you should start saving money to build a new rig in a year or so because even with the upgrades this computer wont last very long.

I have a 350W Power supply. I know that this will need to be upgraded no matter what. So do you suggest I wait a bit and build a whole new rig at a later time? Also, If I do build a new one, will I be able to build one for ~$800 for a good gaming rig?

 

[xsamdagreatx]

my suggestion will be replace your GPU with a radeon 7750 and add an SATA II SSD for you games and windows. this will allow you to play most recent games on medium and some on high. Then start saving money to build a nice gaming desktop in the future. 800 dollars thats a good amount the more money you save the better your build will be.

 

[riahim]

Best answer selected by riahim.