My usb port broke. Bought one of these for battery http://cgi.ebay.com/2-1-EU-Plug-char...#ht_2730wt_905
But I need a good and fast way to transfer large files from PC to N900. SD card isn't an option since my computers SD port doesn't work.( I was able to use it before by connecting my n900 through a USB). I'm not a very techy person so opening it and trying to fix it might cause more problems. I'm out of warranty too.

WiFi? There are numerous ways you can transfer files including, but not limited to, FTP, SSH, WGET, or even mounting your windows share (using Wizard Mounter) and just using the built in copy / file manager functions.

Install OpenSSH server on your phone and WinSCP on your Windows PC, then you can login to your phone with WinSCP (it has an explorer style interface) and then you can transfer files through Wifi.

If you also install PuTTY on the PC it intergrates with WinSCP and will give you access to your phones XTerminal's command prompt on your PC's screen.

Yes, but that way is too slow imho.
I connect to my homeserver with ssh to transfer files but can't get anything more than 2-3Mb/s which is way slower than USB.

scp is the simplest method, and should be doable by most. for more speed, perhaps ftp would be faster. there's proftpd in the repos, but I don't think it's a good idea for OP, since he describes himself as a not very techy person.

@garen I can write a step by step howto for scp If you need it.

There is a good Wiki article for SSH that you should read. It also touches on SCP, you should not have any problems after reading it:

http://wiki.maemo.org/SSH

The only other way to get USB speeds is to remove the memory card from the N900, insert it into a USB card reader on your PC, transfer the files and reinsert it into the N900.
If you can't/don't want to do it that way, then you are stuck with the next fastest option which is via WiFi and any of the methods mentioned above.

zipping up the files before transfer will help reduce transfer time as well.

out of all the connectivity options, wifi is probably the second fastest after USB (excluding removing sd card of course). use ftp. it should be faster than using ssh since there's no compression.

I find quite handy the TinySMB app, via Wifi....

The theoretical maximum transfer rate of USB2 is 480Mbps. The theoretical maximum transfer rate of 802.11g WiFi is 54Mbps. I don't see how you can be surprised that it is "way slower than USB".

Buy a cheap MicroSDHC USB adapter. I got one with the 4GB Sandisk SDHC card I bought recently.