These are the specs on your machine:
Dell™ Dimension™ 2400 Series
Microprocessor
Microprocessor type
Intel® Pentium® 4 that runs at 2.2 or 2.4 GHz internally and 400 MHz externally, or 2.266, 2.4, 2.53, 2.66, 2.8, or 3.06 GHz internally and 533 MHz externally.
Intel Celeron® that runs at 2.0, 2.2, 2.3, 2.4, 2.5, 2.6, or 2.7 GHz internally and 400 MHz externally.
L1 cache
8 KB first-level (Pentium 4 and Celeron).
L2 cache
256- or 512-KB (displayed in the system setup program) pipelined-burst, eight-way set associative, write-back SRAM (Pentium 4);
128-KB SRAM that resides in the processor's core. The L2 cache runs at the processor's internal clock speed (Celeron).
System Information
System chip set
Intel 845GV
DMA channels
eight
Interrupt levels
24 APIC mode
System BIOS chip
4 MB (512 KB)
System clock
400- or 533-MHz data rate
Expansion Bus
Bus types
PCI
Bus speed
PCI: 33 MHz
PCI connectors
three
PCI connector size
120 pins
PCI connector data width
(maximum)
32 bits
Memory
Architecture
DDR SDRAM
Memory connectors
two
Memory capacities
128-, 256-, or 512-MB
Minimum memory
128 MB shared DDR SDRAM
NOTE: Between 32 and 64 MB of system memory may be allocated to support graphics, depending on system memory size and other factors.
Maximum memory
1 GB
Memory type
PC2100 (266-MHz) or PC2700 (333-MHz) DDR SDRAM (non-ECC)
Drives
Externally accessible
two 5.25-inch bays
one 3.5-inch bay
Internally accessible
one bay for 1-inch–high IDE hard drive
Ports and Connectors
Externally accessible:
Serial
9-pin connector; 16550C-compatible
Parallel
25-hole connector (bidirectional)
Video
15-hole connector
Keyboard
6-pin mini-DIN connector
Mouse
6-pin mini-DIN connector
USB
two front-panel and four back-panel USB 2.0–compliant connectors
Network
RJ-45 connector
Audio
three back miniature connectors for line-in, line-out, and microphone
Headphone
one front miniature connector for line-out
Internally accessible:
Primary IDE channel
40-pin connector on PCI local bus
Secondary IDE channel
40-pin connector on PCI local bus
Floppy drive (optional)
34-pin connector
Video
Video controller
integrated Intel 3D Extreme Graphics
Audio
Audio controller
integrated audio
Network
Network controller
integrated 10/100 Ethernet
Controls and Lights
Power control
push button
Front-panel power light
solid green for power-on state; blinking green for standby state
Hard-drive access light
green
Power
DC power supply:
Wattage
200 W or 250 W
Heat dissipation
682 or 853 BTU (fully-loaded computer without monitor)
Voltage (see your Owner's Manual for
important voltage setting information)
100 to 120 V at 60 Hz; 200 to 240 V at 50 Hz
Backup battery
3-V CR2032 coin cell
Physical
Height x Width x Depth
36.8 x 18.4 x 42.6 cm
(14.5 x 7.25 x 16.75 inches)
Weight
10.4 kg (23 lb)
Environmental
Temperature:
Operating
10º to 35ºC (50º to 95ºF)
NOTE: At 35°C (95°F), the maximum operating altitude is 914 m (3000 ft).
Storage
–40º to 65ºC (–40º to 149ºF)
Relative humidity
20% to 80% (noncondensing)
Maximum vibration:
Operating
0.25 G at 3 to 200 Hz
Storage
2.20 Grms at 10 to 500 Hz
Maximum shock:
Nonoperating (half-sine pulse)
105 G, 2 ms
Nonoperating (faired-square wave)
32 G with a velocity change of 596.9 cm/sec
(235 inches/sec)
Altitude:
Operating
–15.2 to 3048 m (–50 to 10,000 ft)
NOTE: At 35°C (95°F), the maximum operating altitude is 914 m (3000 ft).
Storage
–15.2 to 10,670 m (–50 to 35,000 ft)
First of all, you can't even put 2 Gb of RAM into it. It will only accept 2 512 Mb chips and those have to be PC2100 (266-MHz) or PC2700 (333-MHz) SDRAM. You just can't buy 2 Gb. So buy 2x 512 for a total of 1 Gb but get the right stuff. Here's a list of what's available to you:
http://www.newegg.com/Product/ProductList.aspx?Submit=Property&Subcategory=147&Description=&Type=&N=2010170147&srchInDesc=&MinPrice=&MaxPrice=&OEMMark=0&PropertyCodeValue=523%3A8476&PropertyCodeValue=524%3A7861&PropertyCodeValue=524%3A7860Yes, one of those PCI video cards you selected should work but be very careful which one you choose as you only have a 200-250 watt power supply.
One of these will likely be your best bet but you'll have to make sure that your power supply is the 250 watt version, not the 200 watt version (there should be a sticker on the power supply itself):
http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=2000380048%204025%201069609642%201068309611&bop=And&CompareItemList=N82E16814130289%2CN82E16814187041%2CN82E16814133233If you've got the 200W version then you'll need to settle for one of these:
http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=2000380048%204025%201069609642%201068309609&bop=And&CompareItemList=N82E16814139151%2CN82E16814102447%2CN82E16814139151REither way, don't expect wonders. As others have mentioned, the technology in your sytem is old, even if the system itself isn't. You're still going to have to turn down graphic settings in game, run lower texture sizes and keep background processes to an absolute minimum but, you will see a slight performance gain and you're only going to be in for about $50.
BTW, don't even think about upgrading the power supply to run a better card. At that point you're just throwing money away because that first list of cards I posted is as good as you can go with this system. At that point it's time to save the money for a new system. You can get one built that will run AH just fine for around $500 and it will absolutely kill what you have now.
Good luck.
