For a Great build I've created you a little cart here.... Ive listed these in terms of importance.. Ram will have the least effect on overall performance, but a great asset to own when using applications such as photoshop or even surfing the internet.
PSU
(The current power supply in your PC is only 250w.. This is an absolute must to replace if you are going to upgrade your computer.)
Cooler Master 460 w (providing more then enough power for graphics card and the option to have multiple hdd/cd/dvd drives.)
Ive had multiple problems with lower end power supplies not being able to pump the juice needed, arriving doa, or going out after 7-8 months. (roswill, logisys)
http://www.newegg.co...N82E16817171046
GPU
(After reveiwing some benchmarks on your current graphics card, you are still running an intergrated card that scored a whopping 39 on the benchmark tool I was looking at. The card listed score 1617. This would give you SUBSTANTIAL gains in terms of performance over what you are currently seeing.)
Best Deal Ive found for great output/performance. PCI-e (All versions of PCI-e a backwards compatible) minimal differnce in performance.
Radeon HD 6750 1 GB 128-bit DDR3 PCI-e 2.1
http://www.newegg.co...ID=3962334&SID=
RAM
(Based on the specs you posted, you actually have (2) 512 mb sticks of ram inside your computer giving you 1gb of ram... now with that being said even tho you have 1 gb already its running at an extremly low Mhz(333....YIKES!)
The best configuration possible to reduce ram controller stress and speed would be (2) 2gb sticks ran in dual channel
http://www.newegg.co...N82E16820231148 - This is the same ram I run in my current system. Never looked back, low cas latency with heat spreaders that will allow for som OC'ing if needed.
TOTAL 204.97 with shipping.