Problemas com som do Skype

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Eu já verifiquei nos tópicos sobre Skype mas não encontrei o problema para meu problema. Utilizava o Skype no Ubuntu 7.10 e funcionava perfeito. Mas troquei o meu pc. por um modelo melhorzinho (placam2n-sli deluxe, processador 4800+ dual, 2 gigas de ram, video mosaico nvidia 8400gs 256mb.  e , hd samsung sataII 250 gigas)instalei o Ubuntu 8.04.1, mas não consigo fazer funcionar o microfone do Skype, ouço muito bem mas não recebem minha voz. testei no mandriva 2008 e funcionou desabilitando o pulseaudio. Mas no Ubuntu não. Será que o meu hardware é imcompativel com o Ubuntu.
mando meu lspci para vcs. Agradeço qualquer ajuda.

00:00.0 RAM memory: nVidia Corporation MCP55 Memory Controller (rev a2)
00:01.0 ISA bridge: nVidia Corporation MCP55 LPC Bridge (rev a3)
00:01.1 SMBus: nVidia Corporation MCP55 SMBus (rev a3)
00:02.0 USB Controller: nVidia Corporation MCP55 USB Controller (rev a1)
00:02.1 USB Controller: nVidia Corporation MCP55 USB Controller (rev a2)
00:04.0 IDE interface: nVidia Corporation MCP55 IDE (rev a1)
00:05.0 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3)
00:05.1 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3)
00:05.2 IDE interface: nVidia Corporation MCP55 SATA Controller (rev a3)
00:06.0 PCI bridge: nVidia Corporation MCP55 PCI bridge (rev a2)
00:06.1 Audio device: nVidia Corporation MCP55 High Definition Audio (rev a2)
00:08.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3)
00:09.0 Bridge: nVidia Corporation MCP55 Ethernet (rev a3)
00:0e.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3)
00:0f.0 PCI bridge: nVidia Corporation MCP55 PCI Express bridge (rev a3)
00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration
00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map
00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller
00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control
01:06.0 Multimedia controller: Philips Semiconductors SAA7130 Video Broadcast Decoder (rev 01)
01:0b.0 FireWire (IEEE 1394): Texas Instruments TSB43AB22/A IEEE-1394a-2000 Controller (PHY/Link)
02:00.0 SATA controller: JMicron Technologies, Inc. JMicron 20360/20363 AHCI Controller (rev 03)
02:00.1 IDE interface: JMicron Technologies, Inc. JMicron 20360/20363 AHCI Controller (rev 03)
03:00.0 VGA compatible controller: nVidia Corporation GeForce 8400 GS (rev a1)