Upload way faster than download

[Anisaz]

My ISP (RDSLink) recently switched me to a FTTH connection I connect to using the built-in WinXP PPPoE software. However the results are pretty weird:

dslreports.com speed test result on 2006-03-31 15:24:39 EST:
176 / 1105
Your download speed : 176 kbps or 22 KB/sec.
Your upload speed is much faster than down.. have you tweaked?
Your upload speed : 1105 kbps or 138.1 KB/sec.

(yes I have tweaked and followed the recommendations)

On www.testmy.net:
197 Kbps or 0.2 Mbps (24 kB/s) download
1346 Kbps or 1.35 Mbps (164 kB/s) upload

The results above are understated though. When downloading from the net I reach a reasonable 90KB/s speed. The real shocker is that on uploading (including torrents) I get upwards of 500KB/s (4Mbit/s)! (the advertised bandwidth of my ISP is 1024Kbit/s). It is interesting to note that the upload reaches speeds above 100KB/s only when there is no simultaneous download.

I would appreciate your help, obviously not to decrease my upload speed , but to bring my download speed up to the mark.

Details:
Win XP PPPoE FTTH
RDSLink 1024Kbit/s
TCP options string = 020405a00103030001010402

MTU = 1480
MTU is optimized for Windows XP PPoE DSL broadband. If not, consider raising MTU to 1500 for optimal throughput.

MSS = 1440
MSS is optimized for Windows XP PPPoE DSL broadband. If not, consider raising your MTU value.

Default TCP Receive Window (RWIN) = 25920
RWIN Scaling (RFC1323) = 0 bits
Unscaled TCP Receive Window = 25920

RWIN is a multiple of MSS
Other RWIN values that might work well with your current MTU/MSS:
506880 (MSS x 44 * scale factor of 8)
253440 (MSS x 44 * scale factor of 4)
126720 (MSS x 44 * scale factor of 2)
63360 (MSS x 44)

bandwidth * delay product (Note this is not a speed test):

Your TCP Window limits you to: 1036.8 kbps (129.6 KBytes/s) @ 200ms
Your TCP Window limits you to: 414.72 kbps (51.84 KBytes/s) @ 500ms

MTU Discovery (RFC1191) = ON

Time to live left = 57 hops
TTL value is ok.

Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000 (0)

[mccoffee]

try leaving the dsl modem off for awile usually stuff that is phyiscal like modem/line that is odd. Leave it off for about 5 mins retest at a few sites still promblem call provider up that is odd.

[Anisaz]

I have no modem. There is an optical fibre connection to a switch cabinet in my apartment building then ftp cable all the way to my network card.

[mccoffee]

that is odd though call the provider whoever sets that up it's something on the netowrk or phyiscal