Finalmente após certo tempo, consegui comprar um novo notebook, mais precisamente um Sim+ 5361 da Positivo Informática, que chegou ontem de tarde. Após remover o Windows 8 e instalar o Ubuntu 13.04, comecei a utilizar normalmente, mas num dado momento apaguei a luz do quarto para assistir um filme, e para não incomodar os olhos, tentei baixar a luminosidade. Resultado: a tela foi direto ao mínimo de luminosidade, e não alterava de modo algum.
Comecei então a procurar soluções que pudessem resolver o problema, mas as que encontrei, que consistia em alterar o "/etc/default/grub", piorou a situação fazendo com que o brilho permanecesse no máximo todo o tempo.
Tentei algumas outras, cujo link já perdi, mas nenhum funcionava, então resolvi criar este tópico. Rodei o comando lspci, e se for de alguma serventia, aqui deixo o resultado:
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
00:16.0 Communication controller: Intel Corporation 7 Series/C210 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 1 (rev c4)
00:1c.1 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 2 (rev c4)
00:1c.2 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 3 (rev c4)
00:1c.3 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 4 (rev c4)
00:1c.4 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 5 (rev c4)
00:1c.5 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 6 (rev c4)
00:1c.6 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 7 (rev c4)
00:1c.7 PCI bridge: Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 8 (rev c4)
00:1d.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation HM75 Express Chipset LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 7 Series Chipset Family 6-port SATA Controller [AHCI mode] (rev 04)
00:1f.3 SMBus: Intel Corporation 7 Series/C210 Series Chipset Family SMBus Controller (rev 04)
01:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8188CE 802.11b/g/n WiFi Adapter (rev 01)
02:00.0 System peripheral: JMicron Technology Corp. SD/MMC Host Controller (rev 80)
02:00.2 SD Host controller: JMicron Technology Corp. Standard SD Host Controller (rev 80)
02:00.3 System peripheral: JMicron Technology Corp. MS Host Controller (rev 80)
02:00.5 Ethernet controller: JMicron Technology Corp. JMC250 PCI Express Gigabit Ethernet Controller (rev 03)
De antemão, deixo meus agradecimento, e cumprimento à todo o fórum do Ubuntued. Passem bem!