if i am on my wireless at home, how can i navigate to my PC to view my photos and mp3s with my n800?

1) Is your PC also on the network at your home?
a) if yes, then you can share your photos and mp3 directories and see them on your tablet.
1. a network share can be mounted on your tablet's filesystem, in much the same manner as your SD (or SDHC) card(s) are mounted.
2. if you have streaming software (UPnP-capable, ideally) installed on your PC, you can connect the mediastreamer software on the tablet to your networked media (on your PC) and access it that way.
b) if no, then you'd need to put your PC on the network, then see option a) above, followed by sub-option 1 and/or 2.

oh... i dont know alot about network security so i have not created a network...

there is no "backdoor"

so, you have a wireless setup at your home, but your PC is not on that network?

if that is so, then there is no way to share files between your PC and your tablet using your "wireless setup".

no, i dont have a shared network...

i have my WiFi router, 2 laptops (one wixp, one ubuntu) , and n800.

so i guess i would like to use my n800 to browse files on my laptops without making a shared network...

I don't think you really understand what's going on here, starting with the term network. Can you access files on one laptop from the other?
(There's no obvious way to set up access from the N800 to the laptops without that.)

Would it be possible to set the PCs as trusted Bluetooth devices, and navigate their files that way?

That can be done with Bluetooth phones, you can view a trusted BT phone's file system on the tablet's File Manager in the Bluetooth section. Would it work with Bluetooth laptops?

They'd have to be less than 10 metres away of course, which might rather limit the effectiveness of it, but would be interesting to know if it's possible.

I have a same kind of question so thought of poppin' in and ask question on top. I have accessed files on my IT using WinSCP on my computer. Can I do the same from my IT. I mean access computer files from my IT instead of making folders sharable on the network in my computer. Both are under WiFi. Coz, using WinSCP I can access all files in my IT but making folders sharable I can only access that particular folder, isn't it? So, I'm wondering if its possible. Thanks.