Looking for parts for a very old computer

I'm looking for some ram to put in this thing but the RAM I tried to put in it didn't fit. Can anyone link me to some that will?

Also, I need to upgrade the video card and sense this thing is so old, I know i'll probably need a AGP card. I'm sorry to ask you guys but, can someone link me to something that will go in this as well? It needs to work with Windows 7. If such a thing exist, it would be great!

Im sorry to make you guys go on a scavenger hunt, I just don't know what im lookin for.

Here are my computer specs. I am aware of the issues you may see with this build. It is a very old computer.

Field Value
Computer
Operating System Windows 7 Ultimate Media Center Edition
OS Service Pack Service Pack 1
DirectX 4.09.00.0904 (DirectX 9.0c)

Motherboard
CPU Type Intel Pentium 4, 3000 MHz (15 x 200)
Motherboard Name Dell Dimension 3000
Motherboard Chipset Intel Morgan Hill i865GV
System Memory 512 MB (PC3200 DDR SDRAM)
BIOS Type Phoenix (11/08/04)
Communication Port Communications Port (COM1)
Communication Port ECP Printer Port (LPT1)

Display
Video Adapter Standard VGA Graphics Adapter (832 KB)
3D Accelerator Intel Extreme Graphics 2
Monitor HP 23xi IPS LED Backlit Monitor [NoDB] (3CM4020BLC)

Multimedia
Audio Adapter Intel 82801EB ICH5 - AC'97 Audio Controller [A-2/A-3]

Storage
IDE Controller Intel(R) 82801EB Ultra ATA Storage Controllers - 24DB
Floppy Drive Floppy disk drive
Disk Drive WDC WD400BB-75JHC0 ATA Device (37 GB, IDE)
Disk Drive SanDisk Cruzer USB Device (7 GB, USB)
Optical Drive SanDisk Cruzer USB Device
Optical Drive TSSTcorp CD-RW TS-H292B ATA Device
SMART Hard Disks Status OK

Partitions
C: (NTFS) 34310 MB (959 MB free)

Input
Keyboard Standard PS/2 Keyboard
Mouse HID-compliant mouse
Mouse HID-compliant mouse

Network
Network Adapter Intel(R) PRO/100 VE Network Connection
Network Adapter NETGEAR WNDA3100v2 N600 Wireless Dual Band USB Adapter (192.168.0.117)
Modem Intel(R) 537EP V9x DF PCI Modem

Peripherals
Printer Fax
Printer Microsoft XPS Document Writer
USB1 Controller Intel 82801EB ICH5 - USB Controller [A-2/A-3]
USB1 Controller Intel 82801EB ICH5 - USB Controller [A-2/A-3]
USB1 Controller Intel 82801EB ICH5 - USB Controller [A-2/A-3]
USB2 Controller Intel 82801EB ICH5 - Enhanced USB2 Controller [A-2/A-3]
USB Device HP Wireless Mouse
USB Device NETGEAR WNDA3100v2 N600 Wireless Dual Band USB Adapter
USB Device USB Input Device
USB Device USB Mass Storage Device