Two NVIDIA cards at hand - which one to use?

Hi, I have these two NVIDIA cards. Currently I'm using the Quattro FX 1800 on my i5 because it has larger memory. In areas with lots of autogen I get blue flashes and sometimes freezes. Would the GTS with its higher gpu speed improve performance? It has a smaller memory.

GPU-Prozessor: GeForce GTS 250

Treiberversion: 320.49

Direct3D-API-Version: 10

CUDA-Kerne: 128

Kerntakt: 740 MHz

Shadertakt: 1836 MHz

Speicher-Datenrate: 2200 MHz

Speicherschnittstelle: 256-Bit

Gesamter verfügbarer Grafikspeicher: 2047 MB

Dedizierter Videospeicher: 512 MB GDDR3

System-Videospeicher: 0 MB

Freigegebener Systemspeicher: 1535 MB

Video-BIOS-Version: 62.92.62.00.10

IRQ: 16

Bus: PCI Express x16

GPU-Prozessor: Quadro FX 1800

Treiberversion: 333.11

Direct3D-API-Version: 10

CUDA-Kerne: 64

Kerntakt: 550 MHz

Shadertakt: 1375 MHz

Speicher-Datenrate: 1600 MHz

Speicherschnittstelle: 192-Bit

Gesamter verfügbarer Grafikspeicher: 4351 MB

Dedizierter Videospeicher: 768 MB GDDR3

System-Videospeicher: 0 MB

Freigegebener Systemspeicher: 3583 MB

Video-BIOS-Version: 62.94.6E.00.19

IRQ: Not used

Bus: PCI Express x16 Gen2

Thanks!