Internet lost sometimes for unknown reason

Hi, I've seen lots of good help on this site with internet problems, so let me post my problem. I get my internet connection from Wi-Fi, but many times even though the connection appears to be good in the bottom Right of the screen and in the "Connect to" box, nonetheless many times the connection is very slow or it stops altogether. Sometimes it resumes quickly, sometimes after a while, and sometimes I have to log off and come back or even restart my computer for it to work, and sometimes even that doesn't help and I just have to wait a long time till it comes back. It's true that sometimes there is something wrong with the connection (though I don't know what), but sometimes I know for sure that it's the computer that has the problem since if I try getting a connection with an other device (ipod) using the same Wi-Fi connection, the device works but not my computer, so there has to be something wrong with my computer that causes this to happen, though like I said the connection icon shows that all is well, so I have no idea what's going on.

Here is my computer information:
OS Version: Microsoft® Windows Vista Home Premium, Service Pack 2, 32 bit
Processor: AMD Athlon Dual-Core QL-62, x64 Family 17 Model 3 Stepping 1
Processor Count: 2
RAM: 1789 Mb
Graphics Card: NVIDIA GeForce 8200M G, 256 Mb
Hard Drives: C: Total - 227333 MB, Free - 34161 MB; D: Total - 11137 MB, Free - 1870 MB;
Motherboard: Wistron, 303C
Antivirus: AVG Internet Security 2013, Updated and Enabled

In my device manager I have 2 network adapters:
1) Atheros AR5007 802.11b/g WiFi Adapter version 7.6).
2) NVIDIA nForce 10/100/1000 Mbps Networking Controller.
When I press "update driver" both say that the software is updated already and is the current version.

I typed IPCONFIG /ALL in the Command prompt, and this is what came up.
Host Name . . . . . . . . . . . . : SMILEY
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Mixed
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : NVIDIA nForce 10/100/1000 Mbps Networking
Controller
Physical Address. . . . . . . . . : (tell me if relevant)
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

Wireless LAN adapter Wireless Network Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Atheros AR5007 802.11b/g WiFi Adapter
Physical Address. . . . . . . . . : 00-24-2B-1C-46-15
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::9874:c657:eead:27ed%10(Preferred)
IPv4 Address. . . . . . . . . . . : (tell me if the number is relevant)
Subnet Mask . . . . . . . . . . . : (tell me if the number is relevant)
Lease Obtained. . . . . . . . . . : Wednesday, May 22, 2013 8:39:28 AM
Lease Expires . . . . . . . . . . : Wednesday, May 22, 2013 12:56:05 PM
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DHCPv6 IAID . . . . . . . . . . . : (tell me if the number is relevant)
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-10-D2-F5-4E-00-24-2B-1C-46-15

DNS Servers . . . . . . . . . . . : (tell me if relevant)
NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter Local Area Connection* 6:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : isatap.{1700962E-95F1-4BBD-99AA-8A5943F5F
CAD}
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 7:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : isatap.{905FA26D-4688-43CF-85F6-46AF8DB7F
D4F}
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 12:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : (tell me if the number is relevant)
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

I hope I provided all the necessary information about my system and internet connection. If anybody could help me I'd really appreciate it.