I need to know what RAM I should use in my Compaq Presario 5000 desktop computer

You have three Ram Memory slots.

EACH ram memory slot's maximum amount is 256MB
Total Maximum Amount for the computer is 768MB.

Uses SDR Sdram ram memory.

[Single Data Rate Sdram. Commonly just referred to as Sdram.

That is a misnomer.
All ram memory from SDR to DDR3 IS Sdram.

Synchronous Dynamic Random Access Memory.

SDR Sdram = Single Data Rate Sdram
DDR Sdram = Double Data Rate Sdram
DDR2 Sdram = Double Data Rate 2 Sdram
DDR3 Sdram = Double Data Rate 3 Sdram

Just thought i would share ]

Uses SDR Sdram that operates at a frequency rate of 133MegaHertz. (133MHz)
Also known as PC133.

Make sure it is,

A) Non-Buffered
B) Non-ECC
C) Low density
D) CAS Latency of 3 (CL3)
E) Uses 3.3 Volts

Here's an example,

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=423457&CatId=828

One more,

http://www.newegg.com/Product/Product.aspx?Item=N82E16820146303

For questions post in a Comment.

Regards,
joecoolvette