I have an older IBM with perameters below.
With a nVidia GeForce FX5200 video card in the AGP slot.
I know it's not much but it runs fine and just sits there doing nothing but crunch BONIC projects, just wondered if I could do better with a GPU that would be able to crunch as well.
I can't add more RAM about the only upgrade I could do is GPU, since it's IDE and fastest CPU for MB.
The first section below is the Video adapter the second is BOINC
___________________________________________________________
NVIDIA System Information report created on: 02/28/2016 12:07:53
System name: IBM

Processor: Intel(R) Pentium(R) 4 CPU 2.40GHz (2392 MHz)
Operating System: Microsoft Windows XP (Service Pack 3)
DirectX version: 9.0c
GPU processor: GeForce FX 5200
ForceWare version: 175.19
Total available graphics memory: 128 MB
Dedicated video memory: 128 MB
System video memory: 0 MB
Shared system memory: 0 MB
Video BIOS version: 4.34.20.18.07
IRQ: 16
Bus: AGP 4X

[Components]

nvCpl.cpl 1.5.2400.14 NVIDIA Control Panel Applet
nvExpBar.dll 1.5.2400.14 NVIDIA Control Panel
nvCplUI.exe 1.5.2400.14 NVIDIA Control Panel
nvWSS.dll 6.14.11.7519 NVIDIA Workstation Server
nvViTvS.dll 6.14.11.7519 NVIDIA Video and TV Server
nvMoblS.dll 6.14.11.7519 NVIDIA Mobile Server
NVMCTRAY.DLL 6.14.11.7519 NVIDIA Media Center Library
NVOGLNT.DLL 6.14.11.7519 NVIDIA Compatible OpenGL ICD
nvDispS.dll 6.14.11.7519 NVIDIA Display Server
NVCPL.DLL 6.14.11.7519 NVIDIA Compatible Windows 2000 Display driver, Version 175.19
NV4_MINI.SYS 6.14.11.7519 NVIDIA Compatible Windows 2000 Miniport Driver, Version 175.19
NV4_DISP.DLL 6.14.11.7519 NVIDIA Compatible Windows 2000 Display driver, Version 175.19
nvGameS.dll 6.14.11.7519 NVIDIA 3D Settings Server

___________________________________________________________
2/28/2016 11:49:05 AM | | cc_config.xml not found - using defaults
2/28/2016 11:49:05 AM | | Starting BOINC client version 7.6.22 for windows_intelx86
2/28/2016 11:49:05 AM | | log flags: file_xfer, sched_ops, task
2/28/2016 11:49:05 AM | | Libraries: libcurl/7.45.0 OpenSSL/1.0.2d zlib/1.2.8
2/28/2016 11:49:05 AM | | Data directory: C:\Documents and Settings\All Users\Application Data\BOINC
2/28/2016 11:49:05 AM | | Running under account Administrator
2/28/2016 11:49:06 AM | | No usable GPUs found
2/28/2016 11:49:06 AM | | Host name: IBM
2/28/2016 11:49:06 AM | | Processor: 1 GenuineIntel Intel(R) Pentium(R) 4 CPU 2.40GHz [Family 15 Model 2 Stepping 9]
2/28/2016 11:49:06 AM | | Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss htt tm pbe
2/28/2016 11:49:06 AM | | OS: Microsoft Windows XP: Professional x86 Edition, Service Pack 3, (05.01.2600.00)
2/28/2016 11:49:06 AM | | Memory: 2.00 GB physical, 3.85 GB virtual
2/28/2016 11:49:06 AM | | Disk: 232.88 GB total, 214.57 GB free

Sorry, no. The GeForce 5xxx series dates back to 2003. To be a 'usable' GPU under BOINC, the card must be supported by either the CUDA or OpenCL programming languages: for nVidia cards, that support started with GeForce 8xxx cards around 2007 - some three generations and four years later than yours.

The best general source that I know for information like that is

https://en.wikipedia.org/wiki/List_of_Nvidia_graphics_processing_units